There have also been interviews where they've talked about how they won't do something unless they can add something new to it. For example, they haven't created a new F-Zero game because no one has really come up with anything to add to F-Zero to make a compelling game, rather than just "It's another F-Zero game".
In I think the same interview, it was discussed that they won't make a game unless it's fun if it's just geometric shapes or basic sprites. The idea there being that a Mario game isn't fun just because it has Mario in it, but if the gameplay is solid then it will be fun despite not having Mario in it. Presumably this also lets them crank out prototypes without having to worry about spinning up art assets to give testers context.
tbh that's probably just a polite way of saying they wont do a new one because ax was a highly expensive commercial failure. there have been 6 mario kart sequels since gx that all broadly fall into the category of 'just another mario kart'
I'd disagree on the Mario Kart example. The core mechanics of that series have stayed roughly the same, but the little additions have created a different, deeper experience:
In I think the same interview, it was discussed that they won't make a game unless it's fun if it's just geometric shapes or basic sprites. The idea there being that a Mario game isn't fun just because it has Mario in it, but if the gameplay is solid then it will be fun despite not having Mario in it. Presumably this also lets them crank out prototypes without having to worry about spinning up art assets to give testers context.