Why did R&B have a very improper evolution?

Black people have always made the best music but after the 1980's when Teddy Riley created New jack swing actually in the late 80's but in my opinin that is how soul music went downhill its no longer traditional just samples of older songs.I like the SOS band,Freddie Jackson,Luther Vandross,Whitney Houston,Even more Motown,70's soul.funk but I think 80's R&B was evolution and PROPER.I never liked 90's or 2000's R&B cause its overtly sexual and trying to be a cheap imitation of rappers and singers are terrible.Do you think R&B could have maintained its traditional soul and let rap be rap.