Just watch the first 50 seconds of this (note things like the camera angles used etc)
And you're right, more people probably do care because she's Cid. One of the "recurring" characters who has had some sort major role in the majority of main-numbered Final Fantasy games, and the first time Cid is female - she is unnecessarily over sexualised. The real kicker here is that it is especially evident when taking her in comparison to the rest of the known XV cast. Though to be quite honest, I imagine any character posed as a mechanic dressed in a similar way would elicit a similar reaction regardless of the namesakes history.
I didn't say reasonable, I said believable as practical (if high-market) everyday fashion. Again in relation to the rest of the known cast, so far Cidney sticks out like a sore thumb compared to everyone else. The guys are wearing what you could reasonably believe teenage/early-20s would be wearing. Is what the guys wearing suitable for combat, not really, but that's pretty much something that falls into suspension of disbelief when their attire would otherwise look relatively normal for who they are.this being a "fantasy based on reality" doesn't mean all the clothes are going to be reasonable. I'd say the guys don't all have reasonable clothing, one girl so far doesn't, and I'm pretty confident we'll see more characters with stupid clothing before we're done with 'em.
Luna is from nobility and is dressed modestly, like wise from the very little of we've seen of Stella since the re-design she's pretty modestly dressed. The Regis looks formal, the leader of the empire looks regal. Cidney, however, looks one jacket zip strip away from being a pole dancer at a roller disco, not something you might reasonably believe someone who works with machines all day would be wearing. Have you ever worked with oil? It's an absolute bastard to wash off your skin and clothes, no-one in their right mind would dress like Cidney is if being a mechanic was their daily profession.
She is so out of place stylistically with the rest of what we've seen thus far. On that note, watch the later footage of them running around the town and tell me how many people you see who are dressed similar to Cidney.
If everyone was going around dressed like they were at a high school roller disco, or all the guys were in leather pants and their pecs showing and all the girls were in frimpy frilly mini skirts and too-small/tight-to-contain-their-boobs-tops, then yeah, it would probably be given more leeway as an "oh Japan, you so crazy" aesthetical choice (not that it's necessarily an any better situation, but that's something for another thread).
But in this case, Cidney is the odd one out, and that's what people are crying fowl over. While character development story-wise, SE don't always have the greatest track record with major female characters (see Raistlin's sexism series) - at least the majority of them post-VI, design wise, haven't fallen into the male voyeurism bracket that plagues the RPG genre.
Perhaps, maybe, people have come to expect (or at least hope for) more from Final Fantasy than needing to show off an over-sexualised token eyecandy female?