1. Most people don't need or want complexity like what you see from the typical low cost Android devices. Remember most of these people are still upgrading from Nokia style feature phones and aren't after a computer in your pocket (just yet).
2. Android in particular is really nasty at the low end. The quality of experience you would get from a tightly optimised and simplified Firefox OS would be immeasurably better. Again. You don't need to have X, Y and Z instead just have X implemented really, really well.
3. The barrier to entry and cost for developing HTML/JS apps is far lower than Java and Objective-C. You really do need a decent PC/Mac to program for either. And we all agree that custom, locally developed apps is vital.