NC and ND are clearly incompatible with GNU/FDL.
CC-BY-SA on the other
hand is incompatible on a technical level only.
That is, the rules
specify that one cannot cross-license, but the
spirit of both licenses
is equal. Allowing CC-BY-SA is only a small step
from requiring
everything to be GNU/FDL. Allowing NC or ND is a
much larger step, and
we could not reasonably consider an article as a
whole to be GFDL if
there are such images in it.
Well, true (although GFDL has that annoying requirement to print/include the license alongside the product, which is why I despise it for images), but I guess that raises the more central question of: what is the big deal about WP being GFDL? My understanding is that GFDL was chosen as the time partly beause it was the most well-known copyleft license suitable for text. If we had that time again, would we still choose GFDL? How about CC-BY-SA? How about CC-BY-NC? What is the killer argument that Wikipedia should be allowed to be reused in a commercial setting? (I obviously don't consider the DVD argument to be a killer argument.)
Brianna
The reason, as far as I see it, is that commerciality should not be an issue: if someone need to charge for material, than he should not be prevented by license restrictions. If anyone wants to print a book of Wikipedia material, they can't if the material is NC. Some parts of the world don't have access to Internet, so printing is the only possibility, and printing costs money.
/ Fred