I've been using these pets for about a year and haven't really noticed them attracting an inordinate amount of aggro. Their fragileness comes from them only having 10 HPs and like a -75% resistance penalty. Basically they can die if you look at them funny. 
On the other hand I've had them survive fairly well even while I'm playing melee type characters if they have plenty of buffs on them. And I can go entire missions without losing them if I'm playing ranged-oriented characters. Basically they are hard to work with and I don't cast them all the time myself but they aren't really broken... at least not anymore.
What's funny is that they originally were supposed to have a Brawl-like attack power. That power was removed before they went live but their original aggressive AI was still in place. The upshot was that for about a month after they were introduced not only were they very fragile but they actively -charged- towards enemies like they were trying to attack them. It was dumb enough to laugh at how silly that was. 
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They do seem to have aggro like crazy. No matter what, if I haven't hit one of my enemies first, the first thing they do when they notice "me" is go for the pet.
Now, on one hand, good. That distracts them and cycles them through an attack they won't be able to use on ME.
On the other hand, STOP KILLIN MAH BUFF PET!
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whoa, serious dejavu. I seem to recall almost this exact thread a little while after they came out 
http://www.fimfiction.net/story/36641/My-Little-Exalt
I think this might have to do with the slightly annoying aggro behavior/rules than the pets themselves.
I've been playing an Ice/Ice Defender alongside my friend's Fire/Fire and enemies will occasionally beeline for me, unprovoked.
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*Shunted this over from Technical Issues*
I just recently aquired the veteran buff pet reward for being subscribed for... a long time. However, I have noticed that they have, what some would describe as, a flaw. They attract enemy attacks beyond belief. Now, I don't mean PvP enemy attacks, those are warrented. What I refer to are the PvE Minions/Lutennant/Boss enemies. It would seem that, unless every single enemy you are going up against in any fight is hit at least once, then they will instantly target your buff pet (which has no attack power, and not enough Hp to survive a single hit). This results in a resummon for the next fight.
Now, I'm not suggesting that these pets should be immune to damage, just that they shouldn't be a priority target for NPC's as, with the aggro generation they have at the moment, hardly makes them worth having. I humbly suggest that their threat generation gets turned down.
Thank you