My understanding is that 24 fps more closely replicates traditional film, while 30 fps replicates traditional television videotape. The difference is subtle, but if your are old enough to remember when television shows started to be shot on tape, rather than film you may remember that the taped shows had a look that I might describe as "too ordinary." Today, with virtually everything on television shot on tape, you may not notice it. But, it's a little like watching someone play act in your living room, vs. watching a film in a theater. Many feel that the "cinematic look" of 24 fps creates a better "fourth wall" between the viewer and the film.
To me, this is a bit ironic because 4K is so hyper-realistic that it virtually erases that fourth wall visually. People demand that digtial cameras record in 4K and then complain about the lack of 24 fps, but honestly, once you cross that 4K bridge I don't see any way to retain anything remotely resembling a cinematic look no matter what frame rate you shoot.