Well I think that Yamaha is showcasing those Scat Voices as a marketing tool.
In order to promote a new product, they have to show that something is actually new in the product. That is why the Scat Voices are featured because they are now including something in a Yamaha arranger that other arrangers had years before.
It would be interesting to see if future demos promote any new things on the T4.

I have shortened my ID to TTG