Sorry, but what do you mean by a "good platform game"? One that work really
well on a console, making it easy to play while being fun at the same time?
I think one of the big allures of SMB is not that it is easy to play, but that it is really hard to play.
But hard in the right way.
Meaning that with practice, you quickly get a return, and feel that you get better and better.
It's a game with an unusual level of frustration while you play.
This level of frustration actually spawned a movement of its own, with people posting videos of people playing SMB and cussing.
That caused more people to know about the game, and get interested in what is this "impossible" game, and can I beat it?
Also minecraft had this factor, and also Terraria. (but not because of frustration, you wanted to share what you built)
So that's one thing you can look at. How to make your players want to share their experience? (on youtube, blogs, etc) And how to make non-players find this shared experience interesting?
There are no easy answers there.
No there aren't. I agree with the social element that you pointed out. That's
definitely how things are progressing.