Would you rather have a "new IP" with tired, cliche gameplay, or fresh, new gameplay with an old IP attached?
I would pick fresh new gameplay. Too bad that isn't really an option these days. It's more like new IP with tired, cliche gameplay or stale IP with tired, cliche gameplay.
And I even like these games. I like Twilight Princess and Super Mario Galaxy. And Nintendo does try some new concepts in these games (but then most developers add some new features to their sequels). But the setting and the characters are stale.
Most games are derivative to an extent. Only a small handful of truly original games come out each generation. Most of the time it's a familiar genre with a hook. Look at a game like Infamous and you might think "big deal, it's just another sandbox game." Well yeah but it's a sandbox game where you're a superhero. It has a little twist to shake things up and you get to see a new setting and meet new characters. A developer isn't going to reinvent the wheel each time but when they're going to do something fairly routine you hope they can spice it up a bit.
But Nintendo doesn't really do that by clinging to their franchises so much. There is no freshness in the setting or the characters. So a big part of the newness is automatically thrown out the window. So you're left with Zelda... where you can turn into a wolf and Mario... in space. It becomes much harder to provide something fresh and exciting to the player when the genre, setting and characters are all generic. You might say I'm selling Twilight Princess short when I'm saying it's just Zelda with a wolf. But for someone that has played the other Zelda game that IS all there is to it aside from a few unique items.
Back on the N64 you look at a game like Banjo-Kazooie. From a gameplay perspective it's really Nintendo doing Super Mario 64 again with a few new ideas and with Rare developing it. But it didn't feel like just more Super Mario 64 because Rare introduced a new IP. All the characters were new (well some of them debuted in Diddy Kong Racing but close enough) and the world was new. That combined with some of the minor gameplay twists made for a refreshing experience. Now of course Rare went nuts with platformers on the N64 and kind of burned that thing out but the first time they did it it worked very well.
Nintendo has this attitude that story and presentation don't matter but that ain't really true. Gameplay is more important but story is just part of good game design. Having interesting characters and an interesting setting helps provide an escape for the player.
When Sony introduces a new IP they might be using a genre that has already been done but they're still creating a new world for the player to explore. That is significant. It's been a long time since Nintendo gave us a new world to explore. And when both companies are mostly sticking to genre games for their core gaming offerings new IP gets the edge.
Now if Nintendo wants to pop out some new gameplay that isn't a glorified mini-game comp or the same old thing with irresponsive controls then that changes everything. But until that happens I'll give Sony the win in a "best of the worst" decision.