The problem is that copyright law is supposed to decentralize the process of making art, moving the power to authorize art from royalty to the marketplace. Labels have no business setting themselves up as arbiters of what art can and can't be made.What? Baldface assertions like "Mashup albums don't hurt the sales of the albums they sample -- at worst, they have no effect on sales, at best they can promote them," with no accompanying data, just hurt their case in my eyes.
I like free music remixes too, but gosh, asking the labels to look the other way when you shove it in their faces is a bit too much, if you ask me.
I must be getting old.