Themes

I'd agree; I've been thinking about this a fair bit with all the confusion caused by multiple versions of bootstrap being available, and it seems to me that UI frameworks are special enough that they should be handled differently. I haven't got all the nuts and bolts worked out, but I'm thinking that really they should be plugins of their own, which could be required by any theme (or other plugin?) that needed them. Their associated JS should be served up separately to any main bundle (which with HTTP2 out now should also go away soon?), and only when required by the current page.