There's a difference between "better" and "vastly superior". The music, exercise and kid friendly multiplatform games are at best marginally better on the HD consoles. There is no significant difference, so you are good to go with any platform. That's why these genres perform well on the Wii, because they aren't second or third rate products.
When it comes to other genres you are usually looking at massive differences between the Wii and HD versions. NfS which you mentioned isn't just a worse looking game on the Wii, it's entirely different and was outsourced to some crappy developer. And this isn't by far the only example. The general rule is that the HD versions have the top developers working on them while the Wii version is made by a second string studio, if not worse. Sure, most games would be better on the HD consoles by default (due to graphics), but not vastly superior like it has been the case this entire generation. And since these games are targeted at the core customers (the people who are informed), the Wii versions flop left and right, because they fail to reach the treshold of being good enough.
Your three examples of Wii games that were better than the HD versions aren't especially good, because no version of the game was really worth buying at the recommended retail price to begin with. Well, perhaps you bought all three of them. Although if I had to take a guess, I would answer "no" on all three.
what you say is true, but lets not kid ourselves here, those exercise, dance and the like are way cheaper to make. Ubisoft even admitted that recently. They are games that dont require alot of power on a system that has little in the first place. Perfect match. All those other genres are much harder to produce for, money and time wise. Companies are not going to their HD teams stop doing what they are doing and essetially remake the game they are making from scratch on another system that might not even yield the same results. Its much cheaper to give the version that wont be hard to make to a lesser dev team and let them get their experience. Yeah it sucks for Wii only owners but hey.
As for your second point, never said they were better on Wii, i said they were damn close or good in their own right, thats just going off of reviews i have read. Not a PoP fan, having played a Spidey game since Web of Shadows (ugh) and i acutually did play Force Unleashed for PS3 AND Wii and while the PS3 version was better (for reasons i wont get into right now) the Wii version was damn fun. that game sold more than a mil on just about every console it was released on.