Yes, any reason I've ever heard against his inclusion can be levelled at a different character who is already in.

Size: they would rescale him
wings: he'd glide (like Charizard, Meta-Knight, and Pit)
Moves: more than enough variety

I've heard some folks say that "he'd be too big" or "he'd be too awkward" but come ON.  The controls are the same no matter who you play as, so the only difference between the characters is their style of movement and attacks.  If they put Ridley in, they'll find a way to make it work and keep it balanced.

I just don't get why some people insist on being so pessimistic.

Why can't this be discussed in the Smash Bros topic? (A: No reason)