I'm well aware of how the Force works, trust me. I've sunk an embarassing amount of time into the lore. I know that it can move individuals to do things that otherwise wouldn't be possible.
The thing is, thus far, drawing power from the Force had to be earned. Controling it had to be earned. It required training and discipline. Not even Anakin, who was Force Jesus, and amongst the strongest Force users of all time, could manage without training.
There are a million different ways that final showdown could've gone down in which Rey used the Force and defeated Ren without neutering his character. Pulling the lightsaber out of the snow should have been enough. If Rey then fought and beat him by exploiting his physical wounds, there really wouldn't have been much of an issue.
But Ren's wounds, while a source of pain that slowed him down, didn't prevent him from fighting. He was deliberate with Finn, and finished him off in seconds after getting knicked. When he went after Rey, he maintained the same fancy choreography, he was swinging and missing, not because he was inaccurate but because he was slow. They should have stayed with that. The movie already established Rey is tough and can scrap. I would have no problems with her fucking up Ren by fighting dirty and/or exploiting his weakness.
Rey winning because she was tough and smart and scrappy would have been a much more satisfying end to that fight than her just finding her zen and hitting the "I win" Force button because, for some reason, she just can.