I'm with you - and on the subject, having been exposed to a hell of a lot of iOS apps, I kind of think the walled-garden has, in many ways, both promoted the 'weird-art' aspect, as well as limited it.
Promoted: there are now more apps out there than ever before, and more app developers, and more app artists. And they're doing interesting and cool things - most of the top 10 games of the last few years have been artistically appealing pieces, which draw you in with a screenshot and keep you engaged with mechanics.
Hindered: I really, really don't want to see a certain color palette being used to burn itself into my retina and shock me into clicking the icon, among hundreds of others, that stands out the most. I can't see another candy-coating, or amber/cyan highlight, again. But, yet .. still they come. Endless streams of cutesy dreck.
That said, I still think the most interesting game/developer art is coming from the indie gaming/open-source world. There's something about, for example, the benign rag doll look and feel of a game like "Human, Fall Flat" that draws me and the kids back into it. It feels like the good ol' days of gaming, and its something I'm sure has an Amiga heritage, somehow. I don't know if there were really opportunities made for the average mobile App Store to entertain such titles ..