This has been the biggest disappointment for me as a new player. I don't want to seem like I'm whining, but gosh is it disappointing, enough to make me write a feedback thread about it.
I can work around the poor pet/hireling AI most of the time, but the huge lack of hirelings that exist at higher levels(especially in diversity in terms of class), and the lack of scaling for summons & hirelings at epic/legendary levels is just disappointing.
Hirelings not being a full replacement for a real person is fine, but they're basically paper at epic levels with how fast they die, and outside of the cleric/fvs (and sometimes rogue) they're nearly useless.
Maybe I'm missing something but I went from "Wow, Byron is awesome!" a few weeks ago to basically not even using hirelings beyond the first few levels because they're a waste of time. With how much fun I'm having with the rest of DDO, this really stood out as the biggest feature that disappointed me the most.