OP, things you're saying about magica regen are invalid. Especialy when you get +%200 regen it's makes a real diffirence in combat. From early to late mid levels items with this enchantment are VITAL and can not be ignored. Even at late levels a mage should have at least +%200 maga regen if she's using more than 3 school in combat.
Also level 10 is way too early to rise any crafting skill to 100. It's equal to making destruction spells useless against enemies that are effectively scaled to your level.
The only spells you need to spam in combat are destruction, maybe alteration if you want to paralyze everybody that gets close. If you need to spam restoration, you are doing it wrong.
Lets do the math here and see how bad mana regen svcks once and for all:
Lets figure out the best out of combat mana regen for a level 30 mage.
Level 30 pure mage altmer with every level going twords magika should have naked 100+50+290 = 440 magicka.
Assume also this mage has the enchanting tree fully perked out at 100 skill. (going by memory with what is possible for these enchants)
head = +60 magicka, +50% mana regen
neck = +60 magicka, fortify destruction 25% (mana regen not on neck pieces)
body = archmage robes +100% mana regen, +50 magicka, -15% cost reduction on all spells
arms = +60 magicka, +40 carry weight (mana regen not on arms)
finger = +60 magicka, +50% mana regen
feet and shield provide no enchants to increase magic or magic regen
So total magicka = 440+60+60+60+60+50 = 730
total magic regen = 50% from resto 2 perks, +100+10+50+ apprentice stone 100 = 310%
Base is 3% * 3.1 = 9.3
mana regen per second out of combat = 730* 9.3% = 68 mana per second.
An expert spell without any reduction I think is about 250 mana per cast.
Expert perk for -50% = 125 per cast
enchants for destruction reduction in above eq = 40% (125 *.6) = 75 per cast, 150 for double cast
In combat mana regen is very much lessed say its 40% = 27 mana per second
In order to use Impact which is required to stop melees from hitting you we need to double cast and fire 1 double cast per second.
Chain double casting our expert level incinerate spell above means we will be out of mana after
680 - 150 = 530 second 0
530 + 27 - 150 = 407 second 1
407 + 27 - 150 = 284 second 2
284 +27- 150 = 161 second 3
161 +27 - 150 = 38 second 4 OOM
5 casts of incinerate with the best enchated gear and perks I can come up with along with the apprentice stone that has a huge 100% (take double damage) weakness to magic. Also all mana regen is shut off while you cast and thus the above may not even work at that speed, you probably need to cast every other second or hold off for 2 seconds and then cast. This means impact is only gotta work on one mob instead of chain casting it on 2 or 3.
THIS svckS! Especialy when if you ignore mana regen and focus on enchanting cost reduction you can cast all destruction spells for free as fast you want.
Therefore mana regen is totally and completly WORTHLESS.