Why bootable ZFS?

Whenever i´ve read something about ZFS and booting, the question arises: Why should i use ZFS for my boot disks. And well, ZFS can´t do anything, that wasn´t possible before at one way or another. But - an this is the kicker - way more efficient and magnitudes faster:

• think about a Live Upgrade that doesn´t need this long cpio run at start
• think about a snapshot whenever you finalized a change on your system. Jump back to a known working snapshot within a second.
• think about the distribution of increments of ZFS via zfs send to all you server?
• think about all the 72 GB harddisks for an operatingsystem that isn´t bigger than 10 Gig. And think about it without thinking about the partition table and future sizes of the operating environment

And this points came into my mind without really thinking about it.