Yes, 'cause gravity is certainly always very realistic in platform games. Uhm...
And yes, Superfrog has charm. Fantastic atmospheric graphics, the character's simple - and is perfect because of it. I can't see how a super-frog can be made much different. It's a frog. It's got a cape. It's superfrog.
And personally, I've never liked the Mario design. Going for more details than the graphics could handle. Looks more like a pixelated mess compared to Superfrog.