That's fine if the musicians allow it or approve of it, but most of them don't.
According to who? Good musicians shouldn't worry about people downloading their music... people will still flock to the store if the album is good, and people will go to their concerts (where more money is made).
Now Izzy2, if you were planning on striking a deal with a record company to give you a "troubled youth" image and overplay your one catchy song to lure people into buying an album that's 90% filler, then you should worry!