It's funny, but you're unintentionally perpetuating what's becoming the new stereotype. Now that the GPL has become mainstream, it's the anti-GPL people who come off as extreme. I'm not saying you're an extremist, but the GPL is not always the root of the problem.

In this case, it's a mutual incompatibility. This is just as much about the CDDL's restrictions as it is the GPL. The CDDL was created after the GPL, and it was an intended incompatibility. The GPL could have been the MIT license and the CDDL might have included a "cannot be distributed with MIT-licensed software" clause.

The point is that now that nobody has an interest in keeping ZFS out of Linux, it's time to relicense! That's all there is to it.