We should not celebrate Marvel/DC when they announce one female-led CBM after dozens of male-led CBMs, though I have no doubt that half this forum will be labelling them "hero".
You know, I think that (assuming it is a good movie) we kind of should. I mean, should it be enough for either company to only have one female-led movie when they have dozens of male-led titles? Should it be good enough for them to simply put a woman on the release rooster and assume that - crash or cash - that will tie over those fans demanding more female representation? No, of course not, and I personally would not accept a single female character as some sort of "appeasement". I want well written, fully developed and independent characters who are treated in an equal fashion to her male peers. That's plural.
However, honestly, I am all for rewarding studios by cheering on any effort to give female and minority characters equal screen time. I think there is a difference between celebrating them moving in a positive direction, and settling for any sort of "charity". Kevin Feige recently made a comment about how if Marvel were to make a Black Widow movie they wouldn't get "credit" for it, and that kind of made me wrinkle my nose. It shouldn't be about getting credit, this isn't a points game. It should be done because you have an interesting rooster of potential characters and you want to diversify your brand and, yes, I personally think you should do it just because it is a good thing to do. But because I honestly believe that - that producing more movies with super heroines (especially those accessible to young adults/teenagers, little girls and boys) - I am so willing to reward studios for their efforts.
They want some sort of cheer and applaud and attention? You know what, sure. I am of the mindset that we as a culture are so in need of more equality in all arenas and that mass media is a MAJOR player in people's perspective that I am willing to throw you guys a freaking parade if that's what it will take. Hell, I haven't seen a single DC movie in theaters since Batman Begins because, to be honest, I'm just not that interested in the vast majority of these characters. Haven't even seen Geen Lantern or MoS, probably will skip out on this whole Bats Vs. Supes thing they're doing. But I would totally show up for a Wonder Woman solo effort. I know a lot of people see that as a bad thing and consider that behavior not indicative of a "true fan" but think of it this way.... What if you're not a fan of space operas, but you went to see GotG because you're an MCU fan? It's kind of like that, only in this case I'm a fan of "Normalizing The Image Of Female/Minority Super Heroes In The Public Consciousness".
Excluding the most pessimistic among us, I think that most of us cheer when we here that our favorite character is going to get put in a movie, don't we? Most of the time we don't react to the news with, "Oh, well, we shouldn't go an celebrate this guy just for making a movie out of Character X because the truth is that comic book movies have been popular for a decade now, and at this point Character X should have already had at least a trilogy." Instead we look at the positive - they are finally seeing the inherent coolness of Character X! - and applaud them for giving us this chance to see them on the big screen at last. Yeah, sure, we typically want to hear what they're doing with said character, we get more or less excited based on the people involved and any plot details that might get leaked, but unless something comes out that really curves our enthusiasm, I'd say most people's reaction is to give the studio a big old cheer because we understand that part of what they're looking for is the publicity that comes with people's excrement.
So I think it is perfectly appropriate to celebrate if it helps promote further diversity from studios. What I don't think is necessarily helpful, however, is turning it into a race for which company can release the first woman super hero or the first black super hero since that makes it seem as if we wouldn't reward similar efforts for different studios. Similarly, I don't see the point in adding stipulations like "she can't have been previously in another film!" I understand where these "conditions" come from: it makes it seem like studios are "afraid" of a character, it seems to minimize the importance of specific characters when other heroes get their own solo release titles, it paints the woman/minority character into the dreaded support role.... Still, I think a studio can still effectively utilize a character in a positive manner even in another hero's film, and if they actually use that movie as a proper launching pad to finally give us a true solo effort than I will support them all the same because the end result will still be a female led CBM.
Think of those demands for a Loki film or the suggestion that they spin-off Hawkeye or who wanted the Spider-Man/X-Men films to introduce characters like Venom/Gambit so that they could eventually have their own titles. Not everyone liked the idea but absolutely no one was saying, "Well, if they give Loki/Hawkeye/Venom/Gambit a film now it wouldn't really count since he's already been introduced in Thor/Avengers/Spider-Man/X-Men!" The idea that those movies wouldn't "count" is crazy! If you were to go into any of the threads were those possibilities were being discussed I think that the majority of posters, even the detractors, would question your logic. The responses would likely range from, "The whole idea is to introduce them to help create demand for their own movie!" to "That's just stupid. It would still be their own film, how would it not count?" Unfortunately, the truth is that when you're discussing female and minority characters, the standards are slightly different because they have to be. Because the industry - and, you know, society in general - has treated them in a specific manner for so long that you pretty much have to take their history of use into account when bringing them to the screen.
Right now, studios are in a position where "Super-White-Dude" properties seem like a sure way to profit to the point were continuing on that path can guarantee at least some level of success. They don't have to be adventurous and really have very little reason to unless we give them some, which means either:
1. Punishing studios by purposefully avoiding new releases until they give us a female/minority lead title.
2. Promoting and celebrating studios that move in a more positive reaction, which includes both financial as well as critical support (ie treating them as "heroes" for giving us more female/minority driven stories).
Personally, while I would absolutely love a Captain Marvel, Spider-Woman, She-Hulk or Black Widow film, I also rather enjoy the other Avengers titles and am looking forward to Dr. Strange and others, so it would kind of depress me if I had to start avoiding the MCU films. I would way rather reward them with ticket sales and promotional hype.
TL;DR: If it means more female/minority led titles I will get out my cheerleader skirt and lead the parade for any studio. Shamelessly.