You can do that with most of the new arrangers, but I don't have 10 or 20 minutes to spend on every style, so I want the Factory styles to sound great from the factory! Is that asking too much?
Or Yamaha style, having a huge database of songspecific user created styles that is freely shared with the community.//. And an easy way to access them directl from USB stick.
PA4x build im styles however cover pretty much everything most people will ever need...