RAP and R&B happened. Pop today still has some rock influences, but it's far more influenced by RAP and R&B, which, ironically, rock was born out of R&B, the R&B of 70 years ago. Anyway, there's no accounting for taste.
That said, not all rock music is good, not even the so-called "good ol' stuff." The good ol' stuff that actually was good is still good-- and is widely esteemed as good even by audiences that primarily consume pop. The Beatles, for example, continue being beloved by pop audiences today. The problem is, there aren't any new Beatles, nothing even close to that level of good, for if there were, you can rest assured it'd become popular, i.e., pop.