besides the GREAT sound this is a big advantage to Yamaha and other players who are sick of spending a fortune upgrading every year or so with a new model.......
I think you're right but Yamaha does have a huge library of styles in which most you can download for free so although not quite an upgrade, it still can keep things a little fresh. I didn't have anywhere near the amount of new styles for Korgs, GEMs and Ketrons I've owned in the past.