> It was always to obviously to make battery life better

I don't think it was about saving battery power. Jobs was smart in convincing people to focus on web stack for apps - Flash was king of rich app experiences, and java [inc applets] for corporate apps. Apps went iOS native batteries got drained in other ways (large video & photos, prolonged use). Just think of the costs, energy and time spent over the next 15 years maintaining multiple code-bases to deliver one service. The web remained open, where as mobile went native and closed-in.