The problem I have with remixes, blends and chopped and screwed music is that sometimes they ruin a perfectly good song.
I've come across stuff on youtube thats absolutely horrible. People get an acapella and put it over a beat that doesn't match. Its not in the same key and oftentimes its offbeat.
I think an original artist (or copyright/publishing holder) should be able to sue if somebody makes an unauthorized remix.
Which begs the question about sampling. I think that an artist should clear all his/her samples with the copyright holder/publishing holder before releasing it to the public. The reason I feel this way is because sometimes rappers have offensive lyrics like killing people, selling drugs, "hanging a nigga from a tree", drugging girls with molly, etc. I wouldn't want somebody to take my music and rap offensive lyrics over my original composition.
Having said that, the internet is so big its like a jungle. People can put stuff out there and its difficult to regulate.