Controversial thought time:
I was just postulating to myself what would the conversation look like if Rey were a male character?
Would a male need to be the son of a famous Jedi to be ultra-powerful, or would we just be content that he was an orphan? Would there be a concern if the male lead were naturally good at fighting/flying? Would our male lead need to be romantically shipped to every single female character the franchise introduced?
I think that was a good question for those that railed against TFA - but not really applicable to what people have expressed about TLJ.
Personally, I was thrilled that a female was going to be a lead. My love of Star Wars is based on the female characters. I have every single Leia action figure ever made (we are honing in on almost 50 just in the 3.75" line), displayed behind glass. I have all the 12" they have made since 1977, including all Sideshow releases. I also have the 2-foot premium statues. I have the corresponding Padme/Amidala stuff, as well, and every female figure that they have released. I also have other Star Wars stuff - but it all relates to scenes Leia or Padme were in - when a new figure comes out, I look at it and say "would this fit into a display with Leia?" (which is why my other "specialty" in collecting is Jabba's Palace stuff).
So when TFA came out, and I saw fans on some Star Wars sites saying things like "Well, I have no problem with female characters, but there has to be a reason for it, not just to be PC," I wanted to strangle them. That's such a stupid statement - basically saying that all characters should be male by default, unless there is a "reason" for them not to be. Those are the kinds of folks that thought TFA was a terrible film and labeled her a "Mary Sue" from the get-go. I also think they were a minority, because the rest of us who are now agreeing that she is pretty much the ultimate "Mary Sue" (which is applied to both genders, although less commonly people call the characters "Gary Stu" or whatever - that was a moniker created for Wesley Crusher) think that they blasted an opportunity to completely turn that on its head.
I know some people seem to disagree, but TFA was set up as a film full of mystery. Rey clearly had memory issues - she wasn't a toddler when she was abandoned, she was a child - can anyone realistically say you wouldn't remember your parents if they had dumped you off somewhere at 6 or 7? And unlike all the male characters you mentioned - they all had backstories. Heck, Bruce Wayne's has been told so many times it's a trope on its own at this point - he fought and trained and used his money to build his gadgets. James Bond was a member of an elite trained special forces division.
Rey just suddenly having the mastery of everything she touches really is the definition of a "Mary Sue". Her gender is really not the issue. The issue is that her character goes against basically everything that has been shown and told in the previous six films about Jedi - how many times did Yoda say "too old..." - he said it about Luke, and even Anakin, who was only 8. I mean, scene after scene in TFA she exhibits these extraordinary abilities she seemingly has mastered. And as I said earlier, the most damning part is - she seems surprised HERSELF. Everything in that film around her points to the fact that she was gifted and trained as a young child - but for whatever reason (given Star Wars, her protection seems most likely), this was blocked from her knowledge and the story of TFA is her starting to recall these things.
If you take that aspect away and say it wasn't there, as some have - then it really is just a terrible Mary Sue story. And that's what TLJ did. While some dismiss it as too obvious - I think that's kind of a cop out, because this isn't M. Night Shamylan here. You can still have hidden stuff and surprises without being illogical. Especially when you see Kylo's huge tantrum once he finds out "the girl" on Jakku is now involved - I don't see how one can come to another conclusion that she was hidden from him to protect her. Or as a weapon against him. The explanation Snoke gives in TLJ about why they care about each other so much before they even meant is just complete weaksauce.
That's why I find the arguments about "well, she didn't need to be anybody" to be kind of silly. No, she didn't, they could have made a different story to begin with - but everything about the story of TFA pointed to her being so, because without it - it just is a terrible film. Not to mention the endless marketing, panels, press conferences, statements, clarifications of statements, etc. that went along with it.
Then you have the other camp who says "well, she probably *is* somebody, you all just want instant gratification" blah blah - in which case, *this* film was terrible because they pretty much laid it all out - Kylo said it, she "searched herself" for it and since she can see so deeply inside of him, it really doesn't make sense to go back to he is lying - and Snoke seemed to confirm this all, as well. So if in the next film, it's all a big "just kidding!" it was just stretched out way too far - for who her parents are to be the entire through-line of three films is just non-inventive and lazy at best.
This is why the whole thing seems like such a mess right now. They have gone and further divided camps - they've lost those of us who wanted the answers to the questions they originally posed, they lost the people who didn't like TFA because they thought it was a Mary Sue story to begin with and could have proven them wrong and made it all make sense, and now they have the people who like what TLJ did who either aren't going to be satisfied if they go back on it, and some who will be if they don't.
It seems easy to just dismiss this all as "well, see, no one would have been happy no matter what they did" - but I just don't buy that. Sure, some people would have fallen into that category, but they are losing people left and right - and no matter how they resolve it, they are going to lose more - when if they had just set forth and told one coherent story, people could have taken it or left it. Star Wars isn't meant to be
that deep - the problem is, TLJ tries to suddenly make it that way, by basically turning everything that was set up in TFA on it's head - and clearly, by the divisive way this film has been received - it didn't work.