As many people have said, even if the Wii had gone 'HD', it wouldn't have changed much. Aside from a few third parties making some additional games focusing on higher end graphics, most third parties focused on the 360 and PS3 right from the start of this gen and ignored the Wii outright.
The only reason the Wii got any attention this gen was because the Wii overtook the other two consoles in marketshare, causing third parties to give it a second glace 2-3 years into this gen once their initial games didn't sell as well as games like WiiFit or Mario Kart. But instead, all they did was put shovelware and inferior games on the system looking for money. This policy has nothing to do with graphics or 'HD'. It has to do with third parties alienating themselves from Nintendo. Increased graphics wouldn't have brought the third parties in. You wouldn't have seen God of War, Assassins Creed or Grand Turismo on the Wii just because it went 'HD'. That's like saying the Dreamcast could have stolen third parties away from the PS2 with a little more ram.
Six upcoming games you should look into:
