I think Blizzard did a marvelous job of making these NPCs behave like the majority of players. The rogue doesn't interrupt squat and seems to go out of his way to break CC, the warrior tank is trying to raid with his fresh level-cap greens and hasn't figured out how to keybind his abilities (much less figured out what his defensive cooldowns are), and the hunter just stands there auto attacking. At least the mage -doesn't- pop every cooldown each wave and get splattered before Oto even targets a mob (which never seems to be the most threatening one. I love how they leave the AoE casters til last).
Heh, yep! I mutter to myself every single time I'm doing the Endless on my Shaman, and sometimes find myself yelling at them as if they'll move, forgetting they're NPCs. XD
It's fun in an irritating way!