I've actually been meaning to make a similar thread. OP is correct BUT that's what made him so great. I'm a HUGE "technical" guy when it comes to rap but I've realized that passion and other intangibles usually lacks with rappers who are great "technically".
Pac's strength was his voice, passion and the conviction(did I use the right word here?) in which he spoke. That's why people were drawn to his music. Take Dear Mama for example. If you write the lyrics down on paper, its one of the "simplest" songs ever. Very easy to memorize and rap along to. But its HOW Pac recited the words that made it a classic song.
Remember: paid rappers are professional recording artists. When Pac got in the booth he put on a PERFORMANCE. That's what made dude so great. It wasn't just about the words, but also about HOW he said the words.