Mobile devices are designed to host a new generation of apps. The Web is great for expedient universal access, but it won't be a universal multi implementation runtime that works better than platform native runtimes. The Web is a pre-touch legacy platform as much as Windows. Take any tablet and try using it as a touch Web device without using native apps to get a feeling for the scope of the problem.
Mobile devices are designed to host a new generation of apps. The Web is great for expedient universal access, but it won't be a universal multi implementation runtime that works better than platform native runtimes. The Web is a pre-touch legacy platform as much as Windows. Take any tablet and try using it as a touch Web device without using native apps to get a feeling for the scope of the problem.