The Arranger keyboard derived from the easy play features that were added to electronic organs.
As they could be made and transported cheaper then an organ, and took less space in the house, they became the new home organ replacement.
Arrangers were never designed for gigging, but testament to there capabilities a number of owners do gig with them very successfully.
When you see workstations demonstrated they show you how to create and makeup sounds and sequences, which shows haw creative they can be to prospective owners.
When you see Arrangers demonstrated, its intros, endings, press a button and it does it for you, and how easy none musicians can knock out a tune with a pre-loaded setup.
Until Pro’s (Top Notch) see how arrangers can be creative, then arrangers will never be treated in Pro circles as anything other then a cheap home keyboard with minimal potential.
The last statement might upset some folks, but I am afraid that’s the current impression out there in the real world.
As to the demos, the Yamahas were great, but just reinforced the easy play, knock out a tune impression that Pro’s have of them. (Mention Clavinova to a lot of Piano players, and you are looked upon as come back when you’ve learnt out to play properly)
The Korg demos I found very disappointing, so disappointing that I transferred them to my main audio system to see if they improved, (Computer speakers are notorious for ruining the sounds of keyboards) but I have to say they were still lacklustre, and didn’t show a fraction of what the Korg keyboards are capable of. (For me they just sounded like cheap boards from years ago)
Korg keyboards can produce some fantastic sounds, so my personal recommendation is; don’t take any notice of those demos and go and listen to one yourself, then you will really hear how good they can be.

Bill