WARNING! WARNING! Overgeneralization alert!
:P
Seriously, there must be a few intelligent rappers out there. Take Will Smith, for instance. Not only has he made some witty rap songs which parents probably won't understand
,
he's become quite the actor.
Also, there have been a few "spiritual" rap bands out there. Take De La Soul. They produced some far-out sounding rap back in the late 80s that was way ahead of their time: ingenious IMO.
PM Dawn also made some 'wise' music.
However, for the most part, I'll agree: rap music is quite shallow.