I have a similar dream, though mine is focussed primarily on usability, user experince extreme speed and ultra-lean semantic markup.
My previous version of OneWeb contained almost no styling at all, to encourage designers to layer on their own without the distraction of my design already on the canvas, but found that the general user cannot see past that and envisage their own design so easily.
Hence, my revised OneWeb v2 (which has been re-written from scratch) does have a clean, minimal design style. I *hope* that users can still envisage implementing their design on top (though I think I may see many just use it as is!).
I haven't sacrificed the lean+clean ideal to achieve this though, in fact I have pushed it harder than ever before.
My demo site at joomlafuture.com weighs at just 114.3Kb without any compression or minification (earning a perfect 100/100 score when I just tested at
tools.pingdom.com/fpt/ 
). That's including the banner image (not included in the template) at 54Kb and and 44.4Kb of (entirely optional and not present by default) webfonts. Yep, that's under 20Kb for a front-page layout with 2 article intros and 14 modules. It isn't hard to slim it down even further than this, though I wanted to keep my code readable to act as a teaching tool.
Of course, it's mobile first, responsive and functions properly with .js disabled (a particular bugbear of mine).
Personally, I would like to see the loading of *every* asset be made optional giving control back to the designer and users and no .js dependancies anywhere. It's hard to see how a oneweb (the W3C meaning) dream can be reached without that level of control or concern about page-weight. (*just my $0.02, take it or leave it*)
Seth