If there is an argument that maintaining this will somehow improve security overall and not just on ancient hardware then I would love to see it. But if the Devs working on it could care less of what the rest of us think, then maybe those Devs should pay their electricity bills to support their toy platforms because I could care less about what they think too ...
Some of the architectures also have different endianess and incredibly complicated peripherals to the cost effective host machines as well meaning that it's actually more power efficient to run native. A headless 100MHz VAXstation for example draws less power than the equivalent host that would be required to provide a full, accurate emulation with peripherals. These aren't arcade machines.
Portability issues is where real hardware benefits. It's where you have battles of unusual register sizes, endianess, host/network order differences, different memory models and memory protection, different performance characteristics, different timings and different exploits.
Unless the emulation is 100% accurate, including timing, which is a really difficult thing to do (look at the effort MAME goes to), then the benefits over real hardware is moot.
Emulators are also expensive to write due to the above, have their own bugs and don't always recreate the bugs in the real hardware (which are sometimes exploitable).
Also, using emulated hardware could cut down the usage of the real pieces, which could then be better studied and preserved. Doing less builds on vintage hardware is, actually, a good idea.
Then again, it's possible that emulation could surface other edge case issues. That's completely orthogonal to the value of non-emulated archaic architectures for this purpose, however.
If it's worse for the rest of the ecosystem, there's a point.
I'd be interested to hear whether or not this is the case from people closer to such a condition, though (ie: OpenBSD, NetBSD, ???).
This is like saying "I don't care if my arcade goes out of business, I'm going to keep the power hungry cabinets alive even though they only get used once every 3 years."
Sounds good to me. Many times (actually most times) I have no need for a "desktop" metaphor on my screen in order to get things done. I actually get more done big jobs done faster without the desktop metaphor in the way.
"... the devs working on them probably could care less what the rest of us think."
That's what makes them so special.
Perhaps in the long run the most "powerful" and sought after computers will not be the ones with the latest chips, but the ones that the user has the most knowledge of and control over.
Can you imagine the old-timer reminiscing: "Remember when computers didn't have backdoors built-in?" or "Remember when you did not have to pay for a license to write programs for hardware you bought?"
Personally, I do wish OpenBSD could somehow regain the popularity it once had and that support for modern hardware like 10GBE and scaling PF throughput w/ multi-core CPUs would improve. I don't know what it would take to bring people back.