If C2 had vector graphics capabilities I'd never use them because doing vector graphics (and doing them well) is a pain in the ass.
And if for some reason I did want to do vector stuff for the web I'd just go back to using Flash, because that's what Flash does. No reason to reinvent the wheel. Especially since Flash has perfected that particular wheel. You can't really expect a small, open-source project run by two guys in their spare time like C2 to compete directly with Adobe in the vector graphics department, especially by implementing it as an afterthought. Making a game editor that exports to HTML5 is already a pretty tall order!
I've always thought that realtime vector animation for the web was a really dumb idea anyway. It just doesn't make sense. It's too CPU intensive. Compression on raster images has always been miles ahead of vector art. Vector art should be used in static design software, and vector animation should be rendered to video similarly to hi-res 3D. I really have no idea why Macromedia didn't just make Flash a raster-based program to begin with.
The only benefit to using vectors is that they're scalable, and raster images don't scale well. When you compare that to all of the benefits raster images get you, there really isn't any comparison at all.
Just my two cents I guess.
TL;DR: I'd be happy if Flash died a horrible, agonizing death, and took Newgrounds with it.