The reason being is...how many serious fighting gamers (outside of Smash players) do you know that owns a Wii?
This is what I'm pointing out too, because to be truthful, all of the Newly Released Capcom fighting games did very well, however TvC did not? Let's remove the fact that it didn't get a US release until now because even in Japan, in contrast to the other recently released Capcom fighting games, this one happened to do the worse.
It's a given that had this game of been released for say, the PS3, you would actually see alot more hype for this game, even over seas here in the US. However many dropped the option to even port this game over simply due to being on a system, that few competitive players opted to own in the first place due to the main reason that it would lack any real fighting games in the first place.
This isn't about why the Wii doesn't have good 3rd parties (which overall it doesn't anyhow), however it pertains to having better accessibility to competitive players, and or fighting gamers. I could only imagine a PS3 release for this game, which would without a doubt draw more players to it.
TvC was a game that should not have been console exclusive. However, with a US release, this could very well be the 2nd Chance that TvC needs.