Wouldn't that be too taxing on battery life? I'd rather have WebGL used for 3D games or visualizations where I at least know the impact beforehand rather than like flash or as a CSS animation alternative.
Mostly, I just want to avoid learning each mobile platform just to make one app. That's been turning me off from mobile development for years. I'd rather use something like Cordova with webgl and hit all mobile platforms in one shot.