I think Madden sales can work either way depending on your agenda.
At the very least, they show a flaw in the "put any game on Wii, make it accessible with motion controls, and it will sell well due to userbase" theory. Obviously this works for certain games (Lego Indy, Guitar Hero, Tiger Woods, Top Spin), and not so much for others (PES, Madden, Smackdown, and I'm willing to bet The Force Unleashed won't come near the 360 version).
Advertising is a silly cop-out. Everyone knows that Madden is out for every platform. Anyone who watches even one football game (or sportscenter broadcast) a week would even know the launch date months in advance. Also baseless is the assertion that Madden is a mediocre cash-in game that was avoided by astute Wii owners. What about Mario Party 8? You can't have "reviewers don't understand" to explain every mediocre game that sells well on the platform and "this game sucks" to explain every decent game that does poorly.
For example (from gamerankings):
Madden 09 Wii: 82%
Tiger Woods 09 Wii: 75%
Yet Tiger does much better, at least relative to the other platforms.
So what conclusion can we draw from this? The most obvious one is that some games are better suited for motion controls, and some aren't. Some games will scale with userbase size from the HD platforms to Wii, some won't. Resident Evil 5, for example, will probably sell more in its first month on PS3 than RE4's lifetime sales on Wii - at 2x the MSRP.
The blanket "X game would sell better on Wii" statement is obviously not true for a lot of the games listed by Jag22, it's silly to think otherwise.