Surely there must be someone at Nintendo HQ that sees they are eroding their legacy and without it there won't be much left. If they play the casual cheapskates game for too long some other toy will come along and they will be gone.
At least Sega went out in style.
The thing about Nintendo, and this has always been true - always - is that they aren't "cheap" so much as they don't overspend where they feel it's counter productive.
The enthusiast game fan, in a sense, wants as much as possible, all the time. Always the highest possible production values, etc. However, this may be irrelevant to the mainstream and the average game customer. The average person, despite some stereotypes that enthusiasts like to build up, doesn't accept pure crap. Certain qualities will turn the mainstream off a product. But they're not really in it for seeing "the art" pushed to the extreme for the sake of it.
This is why COD remains popular even though enthusiasts scoff at the series and try to frame it in the worst possible light; because it does pay attention to nailing certain fundamentals that the mainstream player base desires.
Nintendo uses "production values" where they think they're warranted and can make a nice experience. 3D Mario gets big production values, I strongly suspect, not just because it's 3D. Rather, 3D Mario is about a tactile playground that requires a sophisticated 3D engine with great performance to fully realize in a game play sense. Because the tech is already there, it allows Nintendo's typically strong art department to throw in a lot of nice stuff without focusing on graphics only for the sake of graphics and no other practical benefit. 3D Zelda games also get higher production values in order to render a fantasy world the player is meant to explore in detail, and to create a mood for it. Metroid Prime games had larger budgets to render a dense Metroid world in 3D, etc, and so forth.
Back in the day, Nintendo spend very little on the "production value" side of games like Super Mario World. Only Yoshi's Island was a game where they went all out technologically, because the visual theme both invited it, and required a lot of detail, splashy graphics, and animation to fully realize. The NSMB series seems to have been treated like Mario World; basic visuals, focused on clarity over everything else, nothing to turn off or weird out the mainstream customer. (How people so easily forget that back in the 90s, Yoshi's Island was mocked and trolled hard by gamers and even Nintendo fans for its childish babby graphics. Who wants to play a video game made of crayons? It's the Wind Waker effect.)
To me the biggest real annoyance with NSMB, I would agree, is music reuse - though some of this comes down to taste. People don't complain when the same SMB3 theme is used for the tenth time in a Mario platformer, because they worship that soundtrack. By comparison, NSMB gets nearly pathological hate because everyone got together and decided to insist "bah bah" is the worst thing ever in a game, so they will not treat these tracks as "classics" we should hear over and over.
Ironically, I think the new primary level theme in NSMB U is actually quite nice, and possibly the best piece of music in the NSMB series. The new overworld musics are also very good. I do wonder if Nintendo reused so much of the music due to branding, and preserving what the average person expects to hear from a NSMB title. Again - we don't bitch and gripe when we hear Nintendo music we approve of for the Nth time in a new game. Then it's "a proper preservation of the classics"
