I shouldn't have used the word place-holder, it was the wrong word to use. However, they are not central to the plot, and in terms of...judging a work's value on a scale of "sexism," that's equally important as characterization. Rinoa may have had great characterization (I'm not saying she did, I'm pretty neutral about FF8 except for that nonsensical we-all-grew-up-together thing), but she's reduced to hanging around waiting for Squall and his merry band to solve her problems (until later).
Hope had a decent arc, I'll agree, but it ended with a whimper instead of a bang: him providing the group with these inane pep-talks. The closest thing Snow has to an arc is his arc with Hope, which is again decent but ultimately goes nowhere. Nothing really changes about him. Sazh was alright, but it felt very much like he was just along for the ride.
I pretty much, pretty much, agree that LR was fanservice--except for the fact, of course, that everyone was screaming NO MORE LIGHTNING after XIII and even more so after XIII-2. And the fact that each sequel had HALF the sales of the previous one. So while I understand your point (and in fact I personally did not care for LR too much, for that whole reason--the costume dress-up), I don't think it's applicable in terms of Lightning's status. I called it the moment I finished XIII-2, I knew she'd become a goddess.
As for your final paragraph, I apologize. I didn't mean to strawman you. Nowhere in your post did you discuss diversity, creatures like Red XIII or even black/white all that. We were discussing the complaints about an all-male cast, and you made a comment about males and females. Again, I apologize for misunderstanding you, but what was I supposed to think when we're talking about gender, and then you join the conversation talking about gender?
Well, I won't disagree that they aren't central to the progression of the plot, but there's more to the writing of a game than just the main questline, and I consider characterisation part of that. Fang and Vanille might have progressed the questline, but I don't really consider them part of the game beyond that, because they never felt integrated beyond being the Ragnarok proxy. Sazh, Snow, and Hope all had distinct arcs and motivations of their own, however badly you feel they were handled, and were clearly more integral to the party than Fang and Vanille were, despite their plot cannons pushing them forward.
I agree that sexism should be an important part of discussion as well, and my lack of mention of it here is due to the fact that I don't think it's truly that much of an issue in FFXV. Simply having a mostly male cast doesn't necessarily make it sexist, just boring to look at.
And yeah, once more, I agree with your commentary on LR as well. I didn't care for anything in the FFXIII-verse, tbh, because I felt it was all rather forced and lacklustre, without any of the passion that the other games had. Although, I do think it's worth bringing up one of the things I mentioned in some of my first posts - LR's casting choice is different than FFXV's, in that it concerns an already established character. Even if fans didn't care, there was clearly a good enough reception to her to allow the writers to exploit their internal bias towards her, so I consider it a different situation.
(You could argue that Noctis and co. were already established in Versus, but that was unreleased, and thus I don't believe it applies.)
Again, to the last paragraph, it's fine. My original elaborations included these:
FFX-2 was different, in that, while it was an all-human and all-female cast, it regarded characters that had already been introduced and developed, and had been proven to be (although this is arguable, as with anything) well-written.
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Then, the mostly male cast was announced (12 characters and only 2 of them are females, and they're all human), and I thought; sure, that's disappointing, since I was looking for some variety in who I'm playing as, but that's not anything game-breaking.
I bolded the parts I wanted to emphasise. I've consistently said in my original posts that I had an issue with the all-human aspect of the characters as well, and although that may not have been clear from my original one, I made sure to clarify in my following ones. It was the other posters who decided to zone in on the gender issue, and I replied based on that. That was on the last page, though, so I understand why it might not've come across that way in my recent posts.