A good amount of them know, they just don't care or want to act surprised, because they tried to either downplay the diversity that always front and center, or they were already racist/sexist assholes that can't be white gang-banger, wannabe black hood anymore. While some are really stupid and oblivious, a lot of the others complaining ain't that dumb. The other reason being is that there are so many people that just don't like change. Usually being blinded by nostalgia and falsely thinking everything was perfect or at its best.
As long as Volition does not continually antagonize the old guard fans, they'll be okay. The game looks like it's gonna suffer regardless, because of how rushed it looks, but get something as long as the game is fun and most of its good gameplay features are there.
Honestly, considering we've mostly seen a pre-rendered trailer so far it's honestly hard to tell. There's nothing terribly interesting or unique about it but that could be a failure of advertising(or indicative of bigger problems).
The new characters? They're fine, I guess. People need to accept f the fact this is a reboot, the old characters aren't gonna be involved and the old characters weren't exactly deep to begin with. They OG cast were colorful but they're all pretty one dimensional with approx one defining character trait each(Gat's a cool psycho, Kinzie is a dom nerd, Pierce is probably gay, Oleg is a big russian, Zimos is an autotune pimp, Carlos is that guy who got dragged behind a truck, Shaudi is either stoner girl or uptight ***** depending on which game, Matt is a fanboy hacker dork, Lin was the angry asian girl, Angel was wrestler dude played by famous wrestler dude, etc). So maybe it's good to have a small cast they can focus on? If anything, the best complaints I've seen is that the cast reminds me of the cast from Watch Dogs 2 and this all has kinda of a WD2 vibe, but beyond that it's....I mean, there's not a lot to go off of.
I hope to god they bring back the septic avenger missions though. If it's not fun to play there's no fucking point. Really, that's the entire point of SR to me is it's a bit out there and a lot of fun. Everything else is in service to that.