I think the main reason that main manufactures steer clear of making software arrangers (At least at the moment) is that people tend to run a mile when they hear the words computer, software etc, even though bespoke computers and software are built into virtually every piece of electrical equipment on the market.
One thing I will say though is that once you have had an open keyboard, it would be very difficult to go back to the limitations of a Hardware board. (I know I would have great difficulty)
Times however are changing, so who knows what the future brings, except perhaps that 10 yrs from now I will probably still be playing my Abacus. (Although give it another 2-3 yrs when the Mediastation has matured I may be tempted away from Wersi, But then again in 2-3 yrs the Wersi will also have advanced, so we will have to wait and see)
Enjoy whatever you play

Bill