Try making some before you diss it...

It is a LOT more complex than you think. Although the lead rapper may not be melodic, he (or she) is VERY rhythmical, even if in a 'loose' style that even crooners used to use. And there is often multi-layered r&b-style vocals behind it that are anything but easy to sing!

But the beats, and the backing... They are very much like blues music. It SEEMS like it ought to be easy, but try it and you'll find it VERY hard to not be derivative, and simply copy what you have heard. Just like the blues, it takes a true master rap producer to come up with something phresh.

Rap, reggae, dancehall, hiphop, ALL these styles seem deceptively easy. But try to innovate, rather than just copy, and you find out how hard it is to get it right... (and even copying is really hard with the soundsets that arrangers provide)