I do take Mage occasionally, but Atronach is way too limiting in that it doesn't allow magicka regeneration. I can usually rely on equipment and spells to offset my weakness to magic though, using reflection and absorption, fire shields and the like. Sometimes I supplement my spells with home-made resistance potions when I'm up against something particularly nasty. It works out quite well actually.
They should fix the Atronach by allowing other ways to regain your lost mana. Maybe there are some environmental effects or places where you can svck up some mana, or special trees in the forest that resonate with magic that you can siphon a little off of without damaging the tree, so it will stay healthy and not die (if you take too much). They could also make a rule that if you're within 10 feet of your enemy and he has magic items, you can siphon some of his mana from the items, rendering them either reduced in power or dead, depending on the Dev's preferences. I think a cool animation of a long thin ghostly line vibrating between you (very feint so you can almost not see it) should do well to let you know you're siphoning, and your enemy can't see you doing this, either.
Perhaps there is a very expensive bar in each town that has special beds made of an ancient wood, and there is only one room per town, and sometimes that room is already rented by someone so you either have to wait or kill him to get the room (depending on your character's alignment (how you play it)), and you can only buy 8 nights per month from any one city or you are reported (to someone in the political system) for being magically "energy hungry" and thus someone to be watched ...
The other methods would be in place. Just think they could do so much more with the Atronach birth sign to make it more interesting to play that just capturing souls and svcking the energy out. It's a bit boring to only have one way (or one place) to recharge your magicka.