Most rap and techno makes me want to kick a puppy. That said, judging all rap and techno by what's easy to hear (either on the radio or in general "pop" culture) is like judging Metal by Nelson.

No matter what the genre or subgenre of music, there are always people who inovate and push the envelope in one way or another and there are always people who produce incredibly lame work. Usually one will find that the least threatening music always makes it onto the radio; that's because most people just want to hear something that sounds good; they've got bigger prioretys than music. It's the natural way of things.

Finally, to me someone who calls themself a DJ and plays other people's music in the midst of a light show is not a musician. However, someone who calls themself a DJ, can mix two records together or set a needle down in the middle of a specific song on a specific record and work the controls/record to produce a specific sound, and can do it live is a musician. Big difference folks.