I haven't read to much about mage spells and abilities, but based on the complaints in this thread, I don't think I'll have too much of a problem...
In DA:O and DA2, I almost always played my mage characters an a AoE machine. So if that's what they're best at in DA:I, I'm happy.
In DA:O, I thought there were more spells than necessary. There were a handful of useful ones that you go every playthrough, and a bunch of useless ones that you either had to unlock on the way, or that you just started grabbing after you got all the good ones cos you had to do something when you level up.
In DA2, upgrades were a nice change, I had to grab less useless spells and just upgraded my useful ones instead. But I always felt like there were certain spells, like the ice ones, that you were "supposed" to take, since they worked with cross-class combos, and that if I wasn't taking them, I was doing it wrong.
I'm hoping that DA:I having a smaller spell selection will alleviate a lot of those problems.