I don't think they're intending to be racist, but they're employing a racial stereotype that which, like it or not, most certainly has its roots in white European racism and the demonising of black men. I don't think everyone should be expected to know or understand the problems with this stereotype, but I dont don't think it's a lot to ask people to maybe make an effort to understand these things once they're pointed out rather than go on the defensive and blame the fact they can't cope with their own ignorance on the PC brigade. It IS a racist stereotype and if people want to carry on singing it then go ahead, but they'll be rightly called out for it.
Maybe it's true the game is being sanitised but this isn't an example of that. I've managed to get behind the team and sing my heart out at games for over 25 years without having to sing racist/sexist/homophobic songs and it shouldn't be a big ask going forward to steer clear of this kind of thing. In fact maybe the atmosphere would improve if we could avoid this kind of shit because more people would actually want to join in with the songs.