Sure I do, but not very often, and they don't have much AoE stuff anyway. My thoughts on that are thus:
1. AoE spells aren't often used in conjunction with a group of enemies. Typically the animal companion is going to be front line, attacking up close and personal. If a wizard has guards and that's who the pet is attacking, he isn't going to lay down a fireball spell in the middle of that out of fear of killing the only guys protecting him. He'll wait until they're dead, but at that point the wolf is probably up in his face and he can't do it anymore anyway.
2. Pets have almost exactly the same amount of health as casters in this edition. Every complaint you had about pets surviving a fireball is equally true of a wizard. It's true that a wolf will be more likely to be on the front lines so the points aren't exactly the same, but the wolf basically has a d8 per level, which is about as powerful as it's ever been.
Look, it's becoming clear that this is really the only point of contention that anyone has, so if you want to house rule it, I'm not going to care. My point was not about that, but rather about previous points of combat effectiveness and staying alive on the front lines. I think Juriel's point of having the animal companion run away at 0 hit points to come back when you've rested is probably the best house rule for that so far, so use that if you wish. But I'm excited for my group's gaming session this weekend with a lvl 10 beastmaster ranger in it. I'll come back to this thread after I've seen him in action, and yes, they will be fighting a dragon.