The thing with OpenBSD is that it's probably the most old-school even including its parent, NetBSD. Even though OpenBSD is a research OS, and has modern features often before any other OS, the way you administer and maintain it is much more old-school.
One great example is wifi, you create one config file in /etc/ for each interface, and then decide how you want it to be handled. To control wifi, you use ifconfig as you would any other interface. Why not just treat it as an additional interface and make it work with all the normal Unix type utilities and workflow?
Hmmh? I thought NetBSD was the legacy/retro computing crowd. They still support (at least as 2nd tier architecture) SUN 2 with MC68K, which are more than 30 years old now. I don't quite understand the motivation for that, I must admit. If I would be curating museum machines, wouldn't I want the original software with it? You can't run modern software in a meaningful way on those ancient, quite limited machines, which have less RAM than today's CPUs cache.
NetBSD is a wonderful OS for embedded applications. Having support for a fully static port (the Sun2 port) and for old, generally slow architectures (m68k, VAX) means performance regressions don't go unnoticed, for starters.
I run NetBSD on a system with 24 megs of memory. I don't think this is possible with modern GNU/Linux - one would need an older kernel and something other than systemd, I think.