They have no incentive to do that though. Batman especially brings in the money, and the rest of them are more marketable, especially compared to the Titans who are not Dick and the NTT era crew (Vic, Kory, gar, Raven).
It's also not the fault of that generation of characters that the next generation down can't get their shit together and struggle for relevance. If they need to get rid of another set of characters to flourish, they may not be that great or independent to being with. I want Donna Troy to get her crap sorted out, get better character writing and have a solid direction for once...but I am not even remotely interested in letting go of Wonder Woman to do it.