I would not feel comfortable with the idea that
Microsoft or Yahoo
could take our content, make an encyclopedia out of it
(redistributable, of course), and *not* include an invariant section
amounting to a link back to us.
Do others share this sentiment?
I'll be the token dissenter here. I certainly don't care what
anyone else does with free content--that's why I made it free in
the first place, because my imagination for what uses it might
be put to is limited. Let any take it for any reason--for free
or for profit--as long as they don't commit outright fraud by
claiming that they created it and attach their own copyright
notice, it's still free.
In support of the general idea, though, I should point out that
making the requirement doesn't actually prevent any other uses,
it just makes them non-automatic. Bomis could still grant permission
for uses that violated the GFDL on an individual basis.