Like the twitter explanation for Luke's motivations (both of them
).
Makes a lot of sense.
Re: Rey - she didn't need Jedi training because she spent her whole life alone defending herself. Luke was a looked after farmboy. Anikan was a small child. Both of them needed to learn how to fight. Rey clearly demonstrates her abilities with her staff early on.
She knows how to fix the Falcon because she's similarly been employed since the age of 4 as a technology scrapper. She knows how components work, and work together. She's also clearly smart.
She can effectively fight Kylo Ren because she's got practical experience, and he suffers from "Lindros" syndrome - his force powers have allowed him to fight without needing to be an expert in lightsaber combat (much as Lindros' size let him play with his head down for a long time).
Anyway - that's why I don't see any issue with her abilities.