rap is highly rhythmic poetry. in pop culture it is often mindless talk of dreams which will never come true for most people. Lots of rap, however depicts imagery and emotion, and more often than not uses mathematical subdivisions of time (a.k.a. rhythm) which many people like to catch onto and dance along with.
I find such aspects of music to be artistic.
oxymoron: a figure of speech by which a locution produces an incongruous, seemingly self-contradictory effect, as in "cruel kindness" or "to make haste slowly."