Why do you say OpenBSD stopped "supporting bind"? You mean they don't include it in the base system anymore since the switch to unbound?
I mean.. It's one pkg_add away. It's a weird constraint to give yourself if that was the problem, considering you absolutely had to install it on your replacement ubuntu servers.
The short version is that we wound up not feeling particularly enthused about OpenBSD itself. We have a much better developed framework for handling Ubuntu machines, making it simply easier to have some more Ubuntu machines instead of OpenBSD machines, and we also felt Bind on Ubuntu was likely to be better supported than a ports Bind on OpenBSD. If everything else is equal we're going to make a machine Ubuntu instead of OpenBSD.
I mean.. It's one pkg_add away. It's a weird constraint to give yourself if that was the problem, considering you absolutely had to install it on your replacement ubuntu servers.