Shocking as it may sound not all mobile devices are iOS, in fact most aren't. jQuery mobile lets you target a huge number of devices. See the supported browsers page for a list:
True, performance on older mobile hardware's not great, my old htc hero runs the demos at a pretty glacial pace. But it wasn't so long ago that javascript performance was apparently so poor that web apps would never catch on and remember this is an alpha version so it's going to get quicker.
I do agree native apps are going to be more appropriate in a number of situations though.
I get your point though... 1 click deployment to multiple devices is a great feature.