same reason why rappers now dont "rap" like they used to...
R&B got it wrong years ago by getting rid of the real instruments. I was listening to the Sinatra channel on Serious Satelite and thats the real shit.
The decline of R&B and the decline of rap are closely related. I think it started from rap though, with the restrictions placed on sampling in the mid 90s and the shift from live instrumentals and samples to computer-generated music. Which automatically means less melodic sound, and because the interaction with the instrument is lost, also less creativity. R&B songs used to have melody in them, now it is exactly the same thing being sung in every song, it's annoying as fuck
There was no reason for R&B to be influenced by the sampling restrictions, after all, in R&B you have always had to write your own music, however, a lot of the major labels had the same people working on the interface between rap, pop and R&B, and that's why this happened. The way the most popular and influential music was made had to fit all genres, including rap, and that's what they did. Timbaland is the perfect example of how the transition happened.
If you look at R&B artists like Dwele who make their own music most of the time, they still make great music, just as in the 90s