Just from a quick look, it looks like Moot is trying to take some of the interactions that grew organically out of 4chan and build them into Canvas, then making it easy for the non-technical person. From personal experience, it seems like whenever you try to parameterize and enforce something that was organic, you run the risk of killing it.

Something I think to keep in mind is, that making it easy for the non-artist and non-technical person to create and publish content removes a giant filter that would keep out a lot of trash. The effort "cost" of producing a remix of content is much lower now, so there's going to be more people with half-baked ideas creating garbage, and everyone will shit on them for posting it...bad experiences all around. Meanwhile, those people that would've still created and published good content (had the effort-cost been higher) may view Canvas as being too canned and immature for their time.

That's just my $0.02. Best of luck Moot, wish you had returned my emails :)