While I think that Yamaha features the scat sounds too much in their demos, I think that you are being unfair in inferring that that is all Yamaha has added to the new keyboard.
There are demos of a lot of other voices, and they sound fantastic.
I was blown away by the brush drum demo. Yamaha added over two dozen new drum kits, and they seem much better samples than the T3 drums.
I think that the problem isn't that Yamaha has great scat and bagpipe sounds, but heavily featuring them in their demos when they are not used so often in modern music doesn't make good marketing sense.