And how many of those samples were known before the artist in question put them to use? You should listen to the originals sometime and realize that a lot of those tracks are crap, or boring, and their only redeeming value lies in the looping of a tiny section which was not even selected by the author, hence it can be easily argued that the person who sampled has as much or more creative input than the original sampled track. Yet you can sample any set of household sounds or recordings and that doesn't mean that those sounds have much of a redeeming artistic value.
Track selection in itself is an art form which makes many genres of music actually listenable; no one ever plays House or Breakbeat songs back-to-back without the expectation of them being played in full. So do DJs get 50% of their earnings taken away by the producers? Do they get denied the right to play tracks because that's taking away control from songs? Skilled DJs make songs come alive and have a creative value that may surpass that of the original producers, and I have yet to find anyone who would feel that anyone's rights are being violated for that. I may agree with limitations where the artist might be defamed by the playing of the music (in the case of "Born in the USA" being played in political conventions), but really, when you release a song the ethical expectation that the artist still has full control of the original work in impractical and I have yet to see anyone who claims that, actually be consistent with their thinking.
On the question of sampling, I love Aphex Twin, especially this song, "Avril 14th" http://www.youtube.com/watch?v=MBFXJw7n-fU . Kanye West's "Blame Game" samples it and it accounts for 80% of the melody. But it's an entirely, completely different song; the sample selection is different, tempo was altered, extra sounds were added, a lyrical component was added. It's a different song, and while it might be reasonable that a small portion of profits from the sale of the song might be attributable to the use of the sample, it is an order of magnitude or two below what content industries demand, which is ridiculous and a form of cultural oppression. This argument is further strengthened when, again, there are millions of songs that can be sampled and can be purposely mangled to not resemble the original.
And really, the argument is about as valid as the author of the Amen break going after the entirety of the UK Bass scene, or Roland going after a third of all music ever made in the last 20 years because everyone uses the 808 drum kit without licensed samples.
Culture is built on its own past and until 50 years ago its sharing was permitted freely, even if the extent of copying the mediums allowed was more limited. In the past 4 years electronic music has evolved more than in the past decade, more people are listening and becoming involved in music than ever before, and more culture can be absorbed today by anyone than ever before, and becoming an artist is easier today than at any other point in history. I see no redeeming value in the preservation of an antiquated business model which supports a very small minority, whose role in the determination of culture becomes ever more diluted every passing day.
If you ask me, our obligation towards cultural heritage is subtantially stronger than the maintenance of a market built on an artificial monopoly that was never even considered to be in the interests of society at large (because, as you know, most of the copyright legislation was written by lobbyists representing the largest media conglomerates).