Some of us will NEVER accept ZFS's licensing. The ability to remain absolutely vigilant in regards to licensing immensely helped IBM during the SCO v. IBM debacle in regards to the JFS file system. We have learned this E-X-A-C-T lesson before.
Additionally, since the code originates from Oracle, many of us progress from being vigilant to outright paranoid. Oracle has never been forgiving, warm, soft, nor cuddly. Hell, even Torvalds himself wants Larry Ellison to personally sign off on ever including ZFS into the Linux kernel [0]
[0] https://www.phoronix.com/scan.php?page=news_item&px=Linus-Sa...