"But I was going to the Toschi station to pick up some power converters!"
"I was thinking of submitting my application to the academy this year."
"Looks like I'm going nowhere... I've got to go finish cleaning those droids."
"It just isn't fair. Biggs is right I'm never gonna get outta here!"
"My father didn't fight in the wars, he was a navigator on a spice freighter."
"I want to learn the ways of the force and become a jedi like my father."
This all happens in the first act of A New Hope. Luke has very clearly defined characteristics, traits, hopes, desires, fears, making him a well rounded human person... it is all laid out to be exploited in the next two acts of the movie.
People have a problem with Rey because she has none of these rich character beats. We don't know what's going on with her other than a vague desire to wait for her family... who they might be isn't even hinted at, and that's essential for us to understand WHY she is hell bent on waiting for them (a vague sense of family isn't enough... who are they to her?). So in the next two acts, there is nothing to exploit or build upon. Luke's father was a navigator, Luke is a pilot and wants to joing the academy... we understand why it's so important to him... the father he never knew was in the same field. Simple and effective. It doesn't take much.
"A young jedi named Darth Vader.... he betrayed and murdered your father. Now the Jedi are all but extinct."
A plot twist, further enriching Luke's character and setting up narrative complications and creating a sense of urgency since Luke may be the last Jedi after Ben.
That is a fuck ton of backstory for the audience to chew on in their imaginations. It also made Vader not just THE STOCK VILLAIN, but a personal enemy of Luke's and Ben's. Again, it gives Luke a very well rounded sense of purpose, he has desires, backstory, a goal of revenge (especially after Vader also murders Ben, the only man who's understood him), an obligation to save the universe from the death star, something he never thought possible.... and since he was just a lowly farmboy dreaming of space, it becomes wish fulfillment. What wishes does Rey have that become fulfilled in TFA? Nobody has any idea. Han offers her a job, but she's shown little desire to leave her planet in the first place, so why does it matter? Maz's "they're never coming back." has little substance since we're missing those pieces.
All this adds up to a character who is just sort of there. Too bad a female hero's introduction in this series is handled so poorly.
I am not sure why Abrams and Kasdan chose to make Rey such a blank nothing. I am still willing to give them the benefit of the doubt that this is leading to something major, but so far they are not doing her any favors. So far, she is not a worthy character to take up the mantle. Finn has more going on than she does. That would be like Han having more going on than Luke. Completely backwards.