He could have brought them back in Angel season 5 if he wanted. Well not Doyle, because Glen Quinn is dead. I forgot Jenny did come back via the The First in Amends.
I mean Joss considers it important to the plot, with stuff like FE being dead people or Connor seeing that vision of Darla. I guess the big resurrections like Spike, Darla, Angel and Buffy could be kind of cheap. Most of those had big repercussions to pay for bringing someone back though. The worst is Spike and the amulet nonsense, but even Joss knows that was lame.