A similar evolving process occurs with hardware boards; however you have to buy a complete new board to obtain the updated features.
Example: Users of a Ketron SD1 have to buy a new Audya to get all that it offers, whereas in an open keyboard you just have to buy the new software (Many software updates are free) to give you all the latest features and sounds.
There is one flaw in your reasonning Bill...
At some point in time you will need to upgrade your hardware of your open system to use the latest features.
But this cost much less then buying a new TOTL arranger. Also you can keep all your old stuff, performances and styles and don't need months to et up your new piece of hardware for your performances, its still all there on a software arranger but it includes new stuff and feautures.
Yamaha Genos, Roland Jupiter 80, Ipad pro.