I am in principle happy with female characters even when they take up the mantle of a previously male character; I found Shuri to be just fine in BP2 for example (the movie had other problems, she wasn't it).
But on a critical level I do find myself wondering if this is actually a good way to strengthen female agency and representation. Do I really want characters that are defined by what some man did before? "X, but female" is a whole trope with a slew of problems, and for all the increase in female characters it provides, it does make me question if it's not counterproductive to some extent to simply recast female reflections of male originals. That just doesn't sit well with me on some level, because it raises the whole canard of women being "just as good as men", as if that was some default standard that females are deficient in. That is something I've usually been quite pissed off by in the past.
I want to see ORIGINAL female characters. Of all kinds. But I get that's hard to do, not only because making new characters is difficult, period, but also because it can feel artificial and ancillary in a world dominated by franchise-driven rosters with decades of history across all kinds of media. So I guess we'd need to reach into that bottomless Marvel hat and pull out some good female characters that deserve more spotlight, kind of the way they turned B-tier heroes like Iron-Man into franchise carriers. Not sure who the best candidates are. Marvel has a gazillion things to work with, but when it comes to writing women, perhaps something conceived of in the 1960s or whatever has its own share of problems. I really don't know.