I think (and could be wrong) you aren't using crosswalk, but another exporter of the intel XDK, crosswalk is the one that gives the best performances.
"the reason people do not export for mobile using html is because a huge percentage of people use the stock browser that does not support webgl."
In fact some people are actually doing this (since the whole point of HTML5 is to be playable everywhere, and C2 is really great to that regard), the apk being more a bonus exporter to support even more people at the end, and I think newest android are using chrome as the stock browser, but I could be wrong on that.