If you want attribution as well, there are ways to ensure this,
in the CC Attribution license this is made very clear, but I guess,
this is possible with GPL'd work as well.
No, the GPL specifically does not have an attribution clause because of
the problems that such a clause caused with the BSD license. RMS is in
fact opposed to attribution clauses, and I agree totally for software
projects. For software, attribution clauses give a minor benefit to
the authors, but with major problems. Imagine if RedHat had to give
credit in all of their materials (books, software boxes, ads, etc.) to
every person who has contributed to RedHat GNU/Linux? It would be
totally unmanagable. Also, if they left someone out, they could be
sued for damages.
But with parts of art projects that are not 'tools' (i.e. the score,
etc.), the reasons for attribution clauses might be compelling enough
to warrant their use. But you could take the example of music built
with samples to be a similar case as with RedHat. Looking say 20 years
into the future, where art is made from samples of samples of
samples..., then the attribution list is going to be in the thousands,
if not more. This is the problem with attribution clauses that makes
them almost as bad as regular copyrights in the long run; you would
have to spend so much time/money to make sure you are giving all of the
correct attributions.
The creative commons license Attribution-NonCommercial-ShareAlike 1.0 (and I'm sure the others too) includes the line:
"Your fair use and other rights are in no way affected by the above."
I would view sampling of parts of the work (for example, up to a couple of bars) as fair use and thus not requiring attribution, this to me is the common sense approach.
Claude