In this case, it's the New Marvel Defectors (that's not a thing, internet...it's just my term). New Marvel Defectors generally have a problem with the direction the company is taking in being more socially inclusive (more female characters, Black Captain America, Woman Thor, etc). The biggest complaint I hear is that Marvel's approach constitutes as lazy writing and that instead of repurposing existing characters to take up the mantle of an existing white superhero, they should just make new characters.
Now, let me first state that this IS AT LEAST HALF TRUE. Yes, the Big Two SHOULD be developing new characters and, mainly in DC's case, working a little harder to develop existing characters of color and non-binary characters. However, let's not pretend that this isn't something that's actively happening. There's been an all woman squad of X-Men in a series that's run right up until Secret Wars, I believe. Al Ewing had a great run on Mighty Avengers, a book about Luke Cage's Avengers team that consisted mostly of characters of color. All New Hawkeye is basically a buddy hero book that highlights Kate Bishop every bit as much as Clint Barton. And, of course, before that, Matt Fraction's Hawkeye basically splits up to two individual self sustaining stories, one with Barton vs. the Tracksuit Mafia, the other with Kate Bishop vs. Madame Masque. And of course, there's G. Willow Wilson's Ms. Marvel, which is a great look at identity, race and coming of age. The people that think original inclusion isn't happening just aren't looking close enough.
Second of all, even with creating new characters, it still misses part of the point of representation and what we're telling little kids (because sometimes, we forget that kids read this shit, too). I like Superman. I've liked Superman ever since I was a kid. My first example of what it meant to be a superhero was Superman. When I played Justice League with my friends, I wanted to be Superman. Once, a kid told me that I couldn't be Superman because he was white and I was black. I knew everything there was to know about Superman. I knew and lived by (or at least TRIED to live by) his ideals. But the kid boiled it down to mere skin color because that's all he knew. I'm not calling the kid racist, of course. For him, it was a matter of aesthetics although it speaks to so many levels of colorism.
Despite cynicism being trendy nowadays, the superhero is still hugely tied to the latter day mythologies of modern culture for now and for always. They are fables inextricably tied to the values by which we live, the hope we pass down from generation to generation. They link us. Sometimes, they even shape us. When you tell people to create new characters instead of breaking the gender/color boundaries of the existing franchises, you're telling a whole readership of children that no matter how much they look up to Captain America or Thor, being black or a woman or gay or whatever you are....means that Captain America will always be off limits to them on some level. You saying that a white person is allowed to take that character's place (as has been the case with Captain America, Batman, Daredevil that I can think of right off the bat), but never a black person or a woman. You're essentially chastising them for wanting to have the attributes of an awesome character that they really like.
Although some heroes' obstacles and outlooks on the world are undeniably linked and shaped because of their race, superheroes are not just men and women built on race. They're ideals, principles, morals and deeds. Yes, Static is an awesome superhero (who occasionally suffers from being in bad comics) and yes, he could stand to be built upon and really SHOULD be built upon, but Superman is a legend, an icon. As great a character as he is, Static is NOT Superman. Representation isn't just building a new foundation for an institution. It's about changing transcending barriers and rearranging the way we look at the old one.
