i think that the problem is both ways - in c2 developers and exporter developers (crosswalk/cocoonJS or whoever).
as goes for c2 devs - we work in an environment that has only events and no real programming, which on export creates two JS files and a bunch of XML from which we can't tell much if things go "as planned", therefore we must focus on massively optimizing the game in our event sheets, setting each sprites/elements/items properties correctly, makin' the game work flawlessly. also there's a lot of code that could be probably better optimized, but it's out of our scope since our env. doesnt' allow us to do so.
on the other hand - we have c2 / crosswalk /etc developers who work pretty hard on fixing bugs and stuff, delivering us new features and performance optimization, but in all their tries there always ends up some code that could be optimized better, fixed, and more, which leaves us hanging around not being able to do so ourselves (if you are in programming lands like me)
the point is - if scirra would waste a year for their nonbrowserwrapper just to bring us better performance, better, well everything i think it would be worth it and they could develop a standard in between all of these other wrappers. even at the cost of employin' a few new devs to help with that. gles.js just shows us that it could be done, pretty quickly and nicely. including other features is just "useless" - you need networking - audio - graphics and maybe physics as separate thing - and you got everything you need for your 2D game.