Can someone explain why loading 240k of library files is a negative? Is this a performance issue or a storage issue? If the later, surely consumers don't care about space?
Because loading 50+ kB of code when you probably only need 10 kB of it is really stupid. This is compounded by underpowered mobile devices that can't digest a single-page ExtJS "app" with 2 MB of script.
Simple is best.
performance issue, all this javascript code has to be parsed by the application before it is able to execute it. So you might end up parsing 95% of jquery/jquery mobile code that your application won't use.