The truth is that the GPL is a pretty restrictive license. I don't think it's fair to blame anyone for the fact that it's not compatible with much. That's its defining feature and the main reason people choose it; so if it blocks ZoL, it's working as intended.
Which I consider a great loss. ZFS is fantastic.
I use the BSD 2-clause license on my own stuff, but I can think of situations where I'd rather use GPL.