Hello Pierry
I agree with you, but at the present time only 2 manufactures make keyboards were this is possible, (Wersi & Lionstracs) and these are at the top end of the market.
The only other way is to take a computer and keyboard with you, which for OMB use means additional setup work.
Give it another 5 years or so then the Arranger keyboards and Workstations that we know today will probably be gone, and there will just be controller keyboards were you choose what software modules you require.

Bill