I think Mario is being "overused". Nintendo is there's so many Mario games people don't care anymore. Only fans and younger players will play those games. It feels like Nintendo is running out of ideas for the plumber, now we have Mario Maker, which was supposed to be good, but they forgot that kids play the game, as a result, we have tons of dumb levels, loads of impossible levels (almost), poor level design everywhere... What makes a good Mario game is just that, good level design.
What's next, Nintendo? Mario Kart Maker? Make your own Yoshi on your smartphone? Toad's Factory? Come on...