What I keep noticing in these threads is that the loudest that complain are big fans of the old EU. They compare everything to it, including saying how they'd use story elements from this EU character for the movies instead of the other. They ignore exactly how loud they'd howl over the retread if that did happen, though, while howling over the EP4 retreads for TFA.
I think this fandom of the EU is the core of this. Take Luke. Luke in TLJ is a pretty easy reach from where he was at the end of RotJ if you only consider the cannon in the movies. It's only when you add in his superbadassness from the EU that it becomes unbelievable, because THAT Luke had very different choices to make and situations he was in that don't lead to his exile. But, if you're wedded to the EU, either because you really liked it (eh) or because you enjoyed having encyclopedic SW knowledge and the geek cred that came with it (or both), TLJ Luke is a "slap in the face." Further, you'll always be looking to the books for the flimsy justifications for why those Mary/Gary Sue/Stus did their impossible BS because it only takes a line in a book to say "trained with badass so and so" for that to somehow be "onscreen" enough to justify their magical powers of badassery. But Rey? Rey is better than Luke in the stories -- gets power faster (or so claimed), does more impressive things (or so claimed), and makes better choices (compared to the ones Luke has made between movies). This can't stand, because Luke, so the engine of dismissal kicks in. There's fair overlap with the misogynist crowd who would do it because she's a girl, but I think a lot of it comes just because she's replacing a favored mythology with something that's different.
But, if you consider, Rey in TFA is really Luke at the start of ESB, not ANH. Luke in ANH lives in a small, safe world, on of work, but also comfort. He isn't hungry, or thirsty, he's well clothed, has a home, a loving family, and wants to run off and join the
Empire as a pilot. He gets sucked into the bigger conflict, has his eyes opened, and, by the end of the movie, is sniping soldiers from across a hanger bay, engaging in high-stakes dogfights, and using the force to make an impossible shot. Then, he's a leader of the Rebellion (enough so that they'll sortie into dangerous weather conditions to find him) and is using the force to grab lightsabers at range while injured, kill ATATs with a snowspeeder, and killing ATATs singlehandedly with a grappling hook and grenade. He gets to wander off on his own, free from Rebellion command, and finally faces down one of the most powerful Sith ever and does
okay on his own (loses but escapes).
Now, take Rey. She starts having to clamber through dangerous wrecks in increasingly acrobatic ways to earn enough scrap
to eat. She lives in a wrecked ATAT. She has to fight to keep her things, likely daily. She good at fighting (she knocks off two enforcers pretty easily and kicks the




out of a stormtrooper (granted, Finn)). From here, you get backstory that she's been working on the Falcon for years, and she flies it pretty well, but no where near as well as Chewie or Han would. But, this feat is just too much -- no way a force sensitive pilot can do less than a normal human despite the fact that Anakin was the
only human who could pilot a podracer and at the age of 8. Or that Luke hit an
impossible shot in an X-wing the first time he ever flew a combat mission. Neither with extensive training. Rey is already a capable human -- she has to fight daily to survive in very harsh conditions where she must adapt and be flexible just to grab some scrap so she can eat, where she has to protect her claim from violence, and where her 'benefactor' has no problem sending thugs to steal from her. But, no, she's just way too competent compared to the pampered farmboy because she was better than him. If you compare to Luke from ESB, it's a bit closer.
And, Rey at the end of TFA, does beat Kylo, but Kylo is an apprentice, still -- powerful but raw. This plot point is mentioned a number of times. Further, during the fight, he was already badly wounded, had just killed his father (and was very conflicted about it), and still was beating Rey right up until he reminded her to use the Force. You know, the Force that let Luke make an impossible shot, the Force that let Anakin fly podracers or surf a crashing capital ship to a safe(ish) landing? And, haven't we seen that untrained Force users can often do outrageous things by accident that then take effort to learn how to do on purpose? But, nope, Luke didn't beat Vader in ANH, Rey can't beat Kylo when he's hurt and conflicted in TFA.
And, point of fact, the next time they met, Kylo had to save Rey from Snoke (Luke managed to escape Vader on his own), and then help her survive the guards fight, and then they fought to a standstill over the lightsaber.
As an aside, I was rewatching TLJ with my kids a few months ago and noticed something I missed the first few times through. When Rey is training with the lightsaber at the stone, that scene finishes with her cleanly striking through the stone in one swing (which gets an eye-twitch from Luke). That's a subtle showing of just how strong she is because where else have you seen a lightsaber cut that easily through anything nearly as large and dense? They tend to bounce off of things (and it looked like they had been bouncing off that rock for a loooong time already).