Ernst I played a wizard to max level in EQ/p99. Lots of downtime but it never felt obscene to me.
It also doesn't feel obscene here on MnM either. You really just need to be managing your mana pool constantly, but that to me is the whole core gameplay mechanic of a wizard. Determine when to burst or not based on your current regen rates using the tools you or your group has.
I've grouped with plenty of wizards on MnM, never felt like they weren't contributing. I duod as a ranger + wiz combo and we had no issues with keeping up either.
Hit+Sit is the wizard life.
Big Hit = Big Sit.
Little Hit = Little Sit.
It feels like every one is arguing over how many hits before a sit, but to me it feels like where it should.
The main problem I have is the early level slog can be a bit much but that's why I take the swordsman trait and just get to whacking.