Longer version, see below for the TL;DR
As a developer with a strong background in the development of "classic" web applications I have been thinking about mobile web application architectures. One question that I cannot really seem to answer is: why do you need a framework like Sencha Touch (maybe even jQuery mobile, although it seems way more lightweight)?
Let me elaborate on this: For me, mobile web apps seem highly similar to "classic" web apps with client side MVC. OK, you need to be extra careful when it comes to efficient DOM manipulations, transfer of (static) resources, offline support and a few more things, but apart from this, the only notable difference seems to be the user experience. Users are expecting typical mobile widgets that preferably behave like the native ones. For this reason, I am thinking that frameworks and libraries for client-side MVC, that are used for "classic" web apps, are also sufficient for mobile web apps and that the only necessary addition is a set of mobile-like widgets.
What is the value of frameworks for non-trivial mobile web applications (think enterprise-level with years of development...) over existing frameworks for "classic" (desktop) web application development? What about "classic" web application frameworks + mobile widget sets?