I think the leoric complaint is fairly valid, since getting close enough to confirm whether it's him or Andariel usually means getting killed by a barrage of arrows from his horror archers or a bone spirit. It's not a big deal for druids, necromancers or assassins, but most other chars can't conjure up minions to 'test' the room.
The butcher, of course, is easy to avoid, as are the other 'overpowered' mini bosses like damien and chimera, but leoric can be very risky.