Or possibly writers change the Force to suit their stories?
In the prequels, it's apparently something you start almost as soon as possible, and Anakin was still learning even as a young man in AOTC ten years after starting. Luke's formal training only lasted a matter of weeks or months, then we can assume he honed his understanding and developed his power alone in the relatively short time between ESB and ROTJ, when he returns noticably stronger. Rey pics up the Force even faster than that. She's able to do everything from the mind trick to telekinesis right away.
I agree that it's ridiculous to get annoyed over these changes. I'm all for them because they each work well in their own trilogy. Rey using those Force powers right away is honestly one of my favorite changes because it really suits JJ's style. However, I also think it's ridiculous to say the Force is portrayed consistently between trilogies.