Sencha took a similar approach with ExtJS and it pains me to watch it falling into obscurity. The framework itself is elegant and well thought-out; it seems that everything Backbone and its various offshoots give us now was already available there years ago.
Sencha Touch is growing because they stopped dual-licensing it. Going on my own personal experience, ExtJS doesn't have much mindshare in the circles I care about i.e. valley-style startups.
