When you're managing large numbers of systems in offices and data centers scattered around the globe you can't count on tab completion to ensure your systems reboot online. You need predictable interface names.
eth0 used to be the answer. It was great.
Then along came udev. In solving a rare problem (consistent interface naming in the presence of multiple NICs) it created a much more serious problem (interface names change whenever broken NIC replaced).
Sysadmins have mostly solved this by configuring both eth0 and eth1 even when eth1 doesn't exist yet. It's a PITA but we're ready when udev slams us.
But now with systemd we would have to get out the ouija board to figure out some kind of name like wwp0s29u1u4i6 that's going to take over when a broken NIC is replaced two years hence.
The better solution is to stay with an init system that works well and doesn't get in our way and doesn't cause random problems by starting services in a different order on every boot.