I've no problem with Rey being a force savant, something very special - The One - but nothing was mentioned in the film about that possibility. Maz was probably the best place to do that directly.
MAZ: "I sense you are very strong in the force, far stronger than your fathe... err Luke"
But why put it into expositional dialogue like that? What's the benefit outside of being able to win arguments on the internet much more easily? Not that Force Awakens is a super-subtle film or anything, but her flying the Falcon is immediately followed up by Snoke noticing there's been an awakening strong enough that both he and Kylo have felt it. So I mean, that says
something, right? She also had a vision the likes of which has never been seen in a Star Wars movie before, featuring people she's never met speaking directly to her, which also points the way towards something pretty substantial. Having Maz stop down to directly explain "you might actually blow past the previously established powerlevel ceiling we had installed" is a lot less graceful, I think, as opposed to simply watching this woman figure the shit out for herself and make it work.
I'd still counter that the Force isn't just a power well you can access at will but requires a certain amount of training, guidance and practice to do, that's what I've leanrt from the previous films.
I'd suggest you don't actually learn that from the previous films at all. You learn that from the ancillary merchandising - the books and (especially) the video games. Other people have made the arguments much more thoroughly upthread, but the films (especially the OT) suggest level of training isn't really all that important, and "training" itself is simply a matter of figuring out how to get out of the Force's way when you're tapping into it.
Which is what we see her doing every time she uses it in the film.
Again: I think it says something that Kylo comes straight out the gate being able to pause people, literally pull memories out of their heads, along with force pulling people AND being able to fight with a lightsaber, and almost nobody asked why the film didn't bother to explain how he could do this. They just took it as read that he was well trained because the big Gollum looking Prometheus dude looked big and Prometheus-y.
That seems to be the point at which people start tripping.