Why are you quoting from a 30 odd year old version of the MM?
Because once you've set something up where humanoids are brown, changing them to greens and dark oranges doesn't do as much as you'd like. They still index the same racial groups the original game did. Oh, look they've changed the white people to the variety their diversity advisors told them to, and they've changedI think the color of monster skin is an overblown issue. More variety would help, and certainly can't hurt, but I don't actually think that greens and blues and dark oranges of some of those skin tones actually index real-world racial groups quite as much or as directly as some people would like to argue.
I didn't write a dissertation, but I did touch on the drow. White (pale) good surface elves and dark evil underground elves is biologically silly and racially problematic. Grey and purple dark elves don't solve that. Realistically pale drow and darker surface elves is biologically realistic, and a lot less racially problematic. But they won't do that because walking away from the racially problematic split is going to cost them more than they will make monetarily.You haven't exactly made any kind of actual argument here that leads to your conclusion that WotC and Paizo have done the 'bare minimum'.