Every (legally sold) Nintendo game had the seal. That didn't stop developers from flooding the market with really, really bad games like X-Men and Heroes of the Lance.
Granted, this didn't stop publishers from releasing really terrible NES games like Action52 (of Cheetahmen fame), but of course those were not licensed by Nintendo and did not have the seal of quality. Most of those games were QBASIC-level bad.
Care to back up that assertion? It may be better for the original author, but it's hard to see how it would benefit the community.
Does anyone actually want to browse 200 variants on flappy bird, or "threes," or candy crush?
Realistically, a concept alone is not sufficient.
I bought Threes, then moved to 2048 because while Threes had components like cute tiles, fun voices, and features like showing the next tile, it was still simply easier/quicker to open a new tab and play from there.
Does the existence of Modern Warfare 2 mean we don't want Spec Ops: The Line?
Games can be very similar to previous ones but still offer a new experience.
Not sure what a good equivalent for the App Store would be today. This is, honestly, what the "Editor's Choice" sections are for.
What scares me about this sort of program is the possibility of a similar barrier on applications. An app market with only one word processor would be terrible, but a market with only one flappy bird is probably better than a market with two.