I love all the people who say things like "All rap is about ganstas and thugs and drugs and bitches and hoes." Yes, and all rock is about worshipping the devil and biting the heads off bats. All country music is about a poor schmuck whose wife burns his house down and runs off with his dog. All classical music requires a 100 piece orchestra. All reggae music is about drugs... OK, bad example.
The point is, within any genre there are going to be differences in styles between artists. Some of these differences may be subtle, which is how we know that two different artists are both in the same genre. But some differences are vast. Someone who likes 2Pac can listen to a hip hop artist like Dose One, and think that it is the worst shit they have ever heard. Someone who likes Sole may look at a fan of Obie Trice as an idiot with no taste. There are no hard and fast rules within the genre of hip hop or rap, and anyone who thinks that it is all the same is a fool.
Incidentally, just cause I get pissed when people are ignorant, here's a few hip hop artists who eschew the "thug" mentality: Aesop Rock, Slug (of Atmosphere), Sage Francis, Eyedea, Dose One, Sole, Alias, pretty much everyone from Anticon, Cunninlynguists, Common, A Tribe Called Quest, Zion I, The Grouch, Gift of gab (from Blackalicious), Diverse... There are tons others, but I'm just doing this off the top of my head. Oh, MC Hammer, he's awesome. And of course there's instrumental hip hop like RJD2 or DJ Shadow, but since we're talking strictly rap, I won't take that angle.
Just because the only rap they play on the radio happens to be shit, it does not mean the genre has nothing good to offer. I personally don't like any of the music they play on the country music stations, but Johnny Cash is amazing. Sure, they play him occasionally, but as a general rule it's new country, and I don't happen to like any of it. Mainly because it's all about ganstas and thugs.