Diki, Roland has a stable full of good musicians that demo their gear.
Over the past twenty years, I have known and met many of their great demonstrators..Going way back to the Eric Persing, John Campbell days..

Roland can definitely, still put together a great realtime demo if they choosed to do so..

Likewise, all the major companies has personnel to do the same..

I think for the most part, companies rely on SMF's ..they show what the instruments sound like in an easy to show way..

Since most arranger market customers are home players[don't doubt this to be true including the Tyros2], rather than a pro market[BTW the G800 series was the first line that was geared towards the pro market and not the home market]..
It looks now that Roland and the Other companies too, are content with the home market..