I think you're going to find the average graphical quality of games on the 3DS to be better than that of those on the Wii because it uses a more traditional setup as opposed to the TEV. There aren't too many devs that are really good with the TEV.
I think you will find better graphical games on ds for a few reasons
- 480x240 or whatever screen is compared to huge tv's. the same game on the ds will look better than it on a huge tv.
- also its easier to get away with on handhelds shorter games. people don't get as pissed having on a few hour handheld game versus only feew hour console game. thus with thinking more time spent on graphics means shorter game. thus if shorter games on handhelds they should have better graphics in same thinking. Though not always true. may be they just slack off and make a short game
- dev's excited about 3D. i don't care who you are, working on something advanced technology wise is everyones dream. No developer grows up and wants to make and 8 bit game. They want their vision to be the next crysis (in terms of graphics) the next oblivion (in terms of world), the next gta4 (in terms of oscar winning story, lol jk). Saying that, even though DS isn't the graphics king, ps3/360/ngp all beat it. It has the 3D factor where they will still be excited. People confuse why people don't develop on the wii. It isn't because its nintendo and casual or can't compete with nintendo games. Its because these developers don't want to develop games on essentiall last gen grahics. they want to make their games look amazing, so you go WOW