You're deluding yourself if you think the CDDL hasn't been a major hurdle against ZFS success in the Linux world. ZFS isn't successful in Linux because the CDDL doesn't matter, it's successful despite the fact it does matter because people put a lot more work into it than otherwise needed and work with the licensing and packaging issues involved with that. But saying "it isn't a real problem" is just factually false, no matter how much you don't like that.

If the CDDL simply didn't matter, after all, they could just add it to the source tree and be done with it. I wonder why they haven't done that...