What concerns me is the following:

I own several keyboards including Yamaha keyboards.

Since I am an owner of a Yamaha keyboard, I believe it is very reasonable that:

1) I use yamaha factory styles that were shipped with my keyboard in any public performance or even use it in my own recording and call that recording mine.

2) I transfer some of these styles to another non-yamaha keyboard that I own and perform that style from that keyboard.

3) I create my own styles that are based on the factory styles but with SUFFICIENT modifications to merit an original work of mine. Then I can do with it whatever I want.

As long as Yamaha and all other companies respect the above and do not implement any functionalities that will prevent me from doing the above, I will have no problem with what they say.

I agree that Yamaha factory styles are for those who own the keyboard that has these styles or those who have purchased these styles. But as long as they do not prevent me from copying these styles that I purchased and change them to fit my needs, or port them to another non-yamaha keyboards, I will be happy.