I don't tjink the lack of the WPA2 security protocol can be an excuse for not having ANY WiFi support on MacMini.
For example, each store of our chain in Spain has access points WITHOUT any kind of security: No encryption, and open authentication. That's because we are forced to use certain industrial WiFi terminals, that don't support advanced WPA security.
Of course, our access points only allow connections from certain MAC addresses. And its SSID is hidden. That's all. We've never had any problem.
I'm sure there's many other places with this kind of configuration.
Not having any WiFi because of the lack of WPA2, effectively, sucks. In fact, I almost can't believe it. Sure I've understood it bad.
I also understand that writing a WiFi stack already is a hell of a job...