Yes i get that this is massive change. But Knights of the Fallen Empire showed that Bioware is willing to change things a lot to improve the game. Now we have great focus on story, we just need improved combat. Instead of pressing 1, 2, 3, 4... i would prefer to actually control my lightsaber like in Jedi Knight series. More and more MMOs are adopting combat system that is more and more advanced - why not go ahead and start the work on adding Jedi Knight styled combat system?
Way i see this:
-old Republic has great story, but old (which is not automatically bad) combat system where you are just pressing buttons and hotkeys instead of actually moving your lightsaber or aiming your weapon. Instead of pressing number X to throw my lightsaber to do X damage to target that i selected, why can`t i do what i did in Jedi Knight and hold down right mouse button, aim the lightsaber as it moves trough air so that it hits as many enemies as possible.
For classes that use guns, you just need to look at every shooter game there is.
-Jedi Knight no longer has story (i mean it no longer has anything new added to it as newest game is well over 15 years old), but it has awesome combat system.
Both of these games have something to attract players. Why can`t we have both? It takes very long time to add, but would be huge attraction to new and old players alike. There are always hard core fans who think current system is better, but looking at huge popularity of fighting games and shooters that don´t even have a story, you can bet well made advanced combat system would be huge attraction even if players don´t care about story or MMO aspect. And of course most would still play this for it`s story aspect.