Actually you should wash your dreadlocks, that's a common misconception.
While they have been around as long as hair, the name dreadlocks was created by Rastafarians who view the hairstyle as an important part of their religion. It is from an archaic use of the word dread, which means to hold in awe or reverence.
Now I don't care who has them or why, only that to some it is part of their religion. So yeah, some people are going to act uptight about it it's the way of the world...