I can get behind this sentiment. Spider-Man wasn't made a household name due to PlayStation games. Disney and Marvel made the property huge. Sony doesn't even own the IP the way Nintendo owns Mario or MS owns Master Chief.OP if my mainstream appeal, you mean something like Spiderman, that cannot be achieved via only games.
That guy is in comics, tv shows, super hit movies AND video games.
These game characters like Master Chief and Kretos will have to go beyond video games.
And while Master Chief has other media, none of that stands on its own. They all tie into video games. We are yet to have comics or tv shows starring him that anyone can watch (outside of Halo fans).
To the greater point I don't think MS needs major mascot characters. They need to continue to deliver with their services and game genre diversity something Sony really lacks. Make as many quality games across major genres and make those games easy to access by not requiring gamers to buy specific hardware. I'm glad MS is doing something different than the Japanese game makers.