Yes and no ...
I have my doubts that the majoirty of consumers would look at the best looking Wii games (that truely take advantage of the Wii) and see them as being all that bad. Part of this comes from seeing people favour systems, and continue to buy software for these systems, when the meaningful difference in graphical capabilities is larger than with the Wii.
On top of this, I think there are some genres which are primarily sold based on how realistic a game looks while most genres are not. On top of this, I think that the number of gamers who are primarily motivated by how a game looks are also in the minority.
Now this isn't to say that some Wii games are not being hurt by their graphics (in fact I think that a game like Medal of Honor Heroes 2 was heavily hurt because it looked very sloppy) or that the Wii will not be effected by the graphical capabilities of other systems, but I don't really see this impact being all that important until the next generation begins and the Wii is outperformed by a system with a similar (or possibly better) user interface.
