I think, Doom, that the late nights you refer to are now the Velvet Lounge timetable. And Black Cat is closer to that. The 'new' 9:30 Club is a more grown up place (in a good way...), and the others have filled that more late-night niche.
For me, I say god bless! I am completely cool with late Friday and Saturday shows, but those mid-week shows can be killers. I've skipped Velvet Lounge shows (like the Tyde and Elefant) 'cuz the headliner's not going on until midnight or so, on a school night.
Hell, I was at 9:30 Club four times last week, and for both mid-week shows I was home by 11:00. {yeah}