There are already literally thousands of them on the net, both for free and commercially. Why bother going through the process of having to painstakingly re-create each instruments again?
I know there are a lot of crappy soundfonts out there, but a well made one can offer top of the notch instrument sound, rivaling the commercial soundbanks on offer in the market. Moreover, proprietary instruments can be converted to the SF2 formats with various software, although sometimes a degree of control and flexibility has to be sacrificed. But until such time when the likes of Kontakt or Reason have been ported to iPhone, this is still pretty dang good.
Just think, adding Soundfonts support immediately allow thousands of sounds to be added to thumbjams!
