rap is big in a few countries other than america, though it's mostly other white countries like england or france, or african countries that got improved by white colonizers
that aside, rap, in concept, is absolutely music and at it's best it's music that takes a lot of skill- being able to come up with clever lines that rhyme to a fast paced beat takes intellect, the issue is that most mainstream rap isn't that, it's not complex rhymes and rhytm, it's like you said, sampling and ooga booga'ing
i have the misfortune of hearing modern rap music when i go out sometimes, in places like shops or out of the iphones of people who don't know what headphones are- i've had to listen to a song where a man, no joke, rhymes the word "dick" with the word "dick" about 4-5 times in a row
i don't recall the actual song but it went something like "bitches on my dick, you jealous of my dick, that bootay on my dick, bitches love my dick-" forcing good people, especially white kids, to listen to nigger music oughta be some kinda crime against public decency