This game requires you to either do research before you spend perk points, or you can just examine the trees before placing your points. Also, you can stockpile your points up, and make your decisions later since the only thing you have to do is pick where you want your enhancement perk to go (magicka, health or stamina). All other perks can wait.
It is unreasonable to think that after being able to craft light armor all the way up to Dragonplate/Dragonscale, that you would all of a sudden be able to craft Daedric weapons and/or armor without prior experience in this type of smithing. Yes, it's not entirely fair that the best weapons are in this perk, and you have no way of having these weapons unless you go the heavy armor route, but you need the experience to be able to make them. Also, looking at tree, the line goes down slightly, which should indicate to you that it is not possible to take that perk after having taken the Dragon perk. Perks are designed to be taken going up, or to the side, not down.
Also, take a look at the pictures of the constellations. The smithing is an anvil, so in order to rearrange the perk tree into something along the lines of having separate armor type crafting, and make another section for weapons, they will probably need to make a new picture (say, an axe, or a warhammer, for example). It probably wouldn't be a bad idea to make a separate branch for weapon smithing, so you could learn ebony weapons and then move on to daedric, but not have access to the armors unless you go the heavy armor route.
This is all coming from a person who went the heavy armor route and took the mage stone. I wore some light armor, or cloth robes the entire time until I've made it to the top of Dragonscale armor. After looking at the tree I noticed that this is how it worked. I wanted to have access to Daedric weapons and armor when it came time to level those skills, so I suffered a little and didn't put perks into the light armor tree, even though I wore some of that armor. All these trees take is a little research, perhaps saving some perk points, and then spending them when you're ready. No need to be upset because you didn't look at the "big picture" or pay attention to how this might possibly affect you in your future game play.
Besides, depending on where you are spending your perk points otherwise, just go up the tree and craft your weapons. There is a lot of leveling to be done in the game, and if you want the best armor and weapons, essentially, you have to spend the points to get what you want.