I'm sure I'd enjoy a special level crawling with zombies. Especially if there were several varieties as in Doom 3 (melee, chainsaw, chaingun), and if they'd respawn. To make up for this they'd have to be slow, easy to kill, and stupid, attacking without regard for themselves or their fellows. On the other hand, this could turn out to be an easy variant of the mortuary, and the zombies' stupidity might require specific AI.
Wraiths could be interesting for their teleporting ability, but I'm afraid they'd cause lots of unsatisfactory instadeaths. Especially in a game with so many random factors as a roguelike, players should be able to rely on tactical gameplay, not luck.
Exploding barrels are among the things that make DoomRL a great game to play. It'd be even greater if they'd move. Therefore, Ticks are cool. And yes, they'd be terribly unfair to berserkers.
Cherubs would unfortunately have very little use, which is a shame because they're positively horrific in Doom 3. I can't think of a way to scare the player with a baby 'c' though, without some defining behaviour.