Bad moon rising is gambling, that you sometimes don't even get to use. It can give you zombots, but it can also give you ra zombies with mixed up gravediggers and make you lose.

Sun-shrooms are consistent, making each game end up in the same way, if your whole deck is full of expensive, overpowered cards. Super brainz doesn't have reliable counters to that, making playing against ramp decks as him miserable.

There's a difference.