With systemd it's not so simple.
iface wlan0 inet dhcp
wpa-ssid redacted
wpa-psk "redacted"
It's a bit clunky if I need to take a laptop around to different wifi networks, but I don't do that very much.It actually works rather well but it doesn't have every feature that NetworkManager does.
For non-wifi use cases you probably don't need anything at all (maybe dhcdcd).
* connecting to different wireless networks that use wpa enterprise authentication (which I think some of the bsds only recently added support for)
* bringing up usb networking interfaces via cell phone tethering on demand
* managing multiple different vpn clients and profiles from a single interface
Or do you mean things like
* Bringing up a networking interface with a static ip address
Because I use network manager for the former on laptops, and remove it on servers that only need the latter.
As with many things, yes, it took OpenBSD and FreeBSD longer to get that functionality. The tradeoff is that they delivered a well thought out, consistent, and well-engineered solution, rather than a poorly thought out mess of CADT-driven bloat.