As to the AI being dumb, you're right, but I bet user error is part of your trouble too (no offense ). You need to give your team orders. More specifically, you need to order them into cover, and then you need to support them. When a fight breaks out, order them each into the rear-most cover, one on the left, one on the right. Then get into cover yourself. With three targets to shoot at, the enemies shouldn't kill your dudes very often, and your guys will help out with some damage, keeping shields from going back up, etc (plus power use).

When my allies died, it was almost always because an enemy overran their position, or I had to run away to recover health (leaving the enemies to concentrate on my allies), etc. When you're all positioned well and fighting as a squad, the AI does just fine at making your allies useful. Just keep in mind that your guys are your backup, and it's still you who has to beat the level. If you do it right, your allies won't die very often, but it definitely happens sometimes. When it does, don't revive them till you're stuck. If you're pinned down and know you can't retreat to the next bit of cover without getting shot full of holes, revive your guys, and they'll distract the enemy. Or maybe you can't get close enough to kill some enemies, in which case you should do the same thing. Revive, order your guys into some forward cover, and circle around.

Anyway. Sorry you're having trouble, but I can't say that I agree with you on the allies. They obviously aren't "intelligent," but when you put them in cover and use them as backup, they really are pretty helpful.