Yet another bunch of ideas I have had.
I really love the crafting system of Skyrim, so it's no wonder that I thought to ways to make it even more awesome...
Complexification and completion of the crafting system. I would love to have more, and more complex features in the crafting system.
Here are some ideas that come to my mind.
Ability to
weave clothes.
More
raw materials : mithril, stalhrim, lead, brass, aluminium, tin, copper, wolfram, adamantium, meteoric iron, meteoric glass, frostbite spider silk, moth silk, lain, linen, hemp fibers, cotton, furs, chitins, domina, mother-of-pearl, coral, ironwood, black ironwood, various bones, ivory.
Ability to use gems in alchemy (possibly after breaking them into powder).
Ability to use ores and raw materials in alchemy.
Ability to use food in alchemy.
Variety in leathers and furs induced by the variety among animal pelts (that is, for example, wolf leather and horse leather should have slightly different properties)
Named soulgems, souls having various properties, depending upon the creature they come from. For example, using a fire Atronach soul to enchant an item should provide a bonus to fire-related spells, and possibly a malus to frost-related ones. Maybe a new perk could allow to ignore the malus ?
Ability put
runes on the armors and weapons (engraving or damascening), to endow them with a feable additional effect.
Ability to craft
enchantings that behave in a special way under special circumstances. I have in mind some features present in Daggerfall, for example, weapons that are more or less powerful in holy places, or in daylight, or during the night. This could be further extended. For example, some enchantings could be more powerful under some astronomical circumstance, or during aurora borealis, or at dawn. If you use the soul of a servant of some Daedric Prince X, the weapon could be more powerful near X's altar, but less powerful near some rival Prince Y's altar, or near Stendar's altar. If Grummites are reintroduced through a DLC and if you use a Grummite's soul, the resulting enchanting might be much more powerful under water or under rain. The item could recharge itself slowly under these circumstance, and lose slowly its power under dry weather...
More
special forges, and special enchanting altars and alchemy tables. For example, giving a purpose to the Lunar forge. And possibly relating it to a Solar forge, somewhere. Some Spectral forge would be very nice, too, in order to be able to craft weapons like the Ghostblade (and possibly you'd have to be taught by some Whispmother how to use it). Also, I would love that a DLC add an Ayleid ruin in Southern Skyrim, with possibly a forge dedicated to the crafting of meteoric iron and meteoric glass. Or a forge whith a cold fire transforming water into permanent ice... Maybe also a Daedric forge.
Being able to quench metal. Alchimy should be used to produce
quenching media which would endow the metal with certain properties. Also, Alchemy should be used in producing
special alloys... Another use of alchemy in smithing would allow to create
special fuels for the forge, so that the magical fire produced can have an incidence on the crafted items.
Being able to
create soulgems from ordinary gems. The alchemical properties of the gems should have an incidence on the properties of the resulting gem.
Being able to
craft Sigil stones from morpholiths (this ability should be the reward of an extremely difficult quest, however, since the Sigil stones are supposed to be rare and of an immense value. )
Incidence of harvesting circumstances on the properties of harvested ingredients. For example, some flowers, when cut with a mithril or golden billhood under some lunar phases, may have some special properties.
Potions should be
worth less when they produce both positive and negative effect, and an
additional phase of purification should be added with the perk "Purity", here the player could chose which effect he wants to keep, and which ones he wants to withdraw.
A possibility to learn
recipes from The Gourmet. Also,
infusion recipes.
Possibility to
learn special crafting techniques from forging or enchanting masters, or recipes from specialized alchemists. For example, one could learn special enchantings from a Spriggan or a Hagraven, or special runes from a Dragon, or from an Draugr, or special poison recipes from Falmers, or special smithing techniques by translating ancient Dwemer texts...
Well, ebony is required to forge daedric items in the Atronach Forge. And indeed, it is well known that ebony is a component of what's known as Daedric material. But what if one tried to infuse glass, or stalhrim, or ironwod, or meteoric iron, or any other raw material, wit Daedric fluids? Would it result in
different kinds of Daedric materials? I would like to be able to try such experiments.
Necessity to use some alteration spell to
preserve some ingredients from withering.
Ability to craft ceramics, earthenware, porcelain,
pottery, glass bottles.
Also, crafting poisonous or healing
candles, or
creams,
ointments,
eye drops,
inks for war paints...
New creaturesWell, there is quite a bunch of new creatures I would like to see, either on Skyrim itself or in other places that could be added through DLC.
Ravens
Crows
Rats
Mice
Rock Warblers (Since we can find their eggs, I would love to be able to see them)
Pine Thrush (For the same reason as the previous bird)
Wolverines (because there was a Wolverine Hall in Morrowind, so there must exist wolverines somewhere in Tamriel)
Imps (possibly with Impish staves/weapons/armors/clothes?)
Minotaurs (obviously with more fur than in Cyrodiil, and perhaps with special sets of Minotaurian armors and weapons)
Ogres (Again, possibly with specific item sets)
Megatherium-like creatures/bears (Megatherium were prehistoric ground sloths)
Whoolly rhinos
Cliff Racers (near Morrowind border)
Wereboars
Dwemer walking ballistae
Dwemer ghosts
Real bats (Also, I would see some of them outside caves during the nights. Some aggressive bats carrying diseases would be nice, too. I have already said it, but I would love that the axe called Wings of the Queen of Bats come back from Morrowind, with interesting lore around it... I would love to know, for example, who is the Queen of Bats)
Owls, Whales, Snakes (Weren't they deified by the Nedes?) (Also, if there is a Queen of Bats, I would love to see the Kings and Queens of the hawks, wolves, snakes, moths, owls, whales, bears and foxes)
Spoiler Also, during the Fjori and Holgeir quest, one learn that a snake poisoned them. So it would be logical, lore-wise, to find snake in Skyrim, wouldn't it? I would have loved, by the way, to fight the (now undead) snake responsible for their death in Ansilvund)
Eagles (also mentioned in various lore)
Snow lions
Snow leopards
Snow tigers
Snow hawks
Snow wolves (Not, ice wolves, rather the magical snow wolf from Arena)
Hell hounds
Pheasants
Peafowls, leucistic peafowls
Flies
Clams
Kollops
Sharks
Narwhals
Krakens
Gehenoths
Undead (seleton, draugr and ghost) versions of the various creatures of the game.
Much more variety among Daedra, and Trolls (there were many troll types in the game Dawnstar) (With possibly trollish weapons [that is, rudimentary clubs])
Goblins (in the Fearfrost caverns, near Skyrim border?) and Dreughs, with interesting lore related to them, specific architecture, arts and crafts, culture, society, religion, cooking recipes,...
New Dragon types
Various other wishesAbility to tame wild creatures (you know you want a frostbite spider as a companion! )
Adding a place called Valtheim Keep (We already have Valtheim towers, but Erik in Rorikstead mentions Valtheim Keep. Perhaps the devs had a project for another settlement near from those towers, but hadn't the time to put it in. Well, it could be added through a DLC, then.)
Ability to use improvised weapons (such as a bottle, a spoon, a broom) and even to enchant them

An enchanting ritual, in addition to the other rituals of the College of Winterhold
Unlocking the "Spectral arrow" spell.
High level Falmer archers wearing helmets endowed with a detect life enchanting. It would be much more difficult to sneak on them, and would possibly require illusion spells
Something related to Sai and Ebonarm
Garrotes for assassinations
Slings
Saunas, public bathes, personal bathes
One bonus perk? (The "level 1" perk)
Three new perk trees? (One for each specialization)
A new incursion in the painted world?
Levelled items that evolve with the perks of the player, and don't remain fixed in the way the player found them.
Spears, crossbows, spellmaking, throwing weapons, mounted combat, martial arts? (one may always hope... )