They’re just not timeless. If you were to go back in time to sell your ancestors on a song from the future, a lyric like “me wearing my Oaklies and taking a Polaroid selfie in Times Square” is probably not gonna translate so well. Therefore the song’s message is probably superficial.
Not all hip-hop obviously, Pharcyde are pretty solid lyrically.
I actually have a sub dedicated to calculating how timeless a song is: