Personally I find the style creators on more recent PSR's to be quite easy and intuitive to use. There are tools in there that simplify style creation that previous PSR's did not have (such as copying entire parts from one section to the next). That alone is a huge time saver.

I think what deters a lot of people are several things. Recording drums (even when broken down by parts) is very difficult for many. Keeping bass lines and chord tracks within the predetermined key signature (so that chord recognition is properly applied) can also be hard for some.

Another area of difficulty for many is recording those fills.