There was a period where that kind of kit was usefully usable as (effectively) an X terminal -- you could put Linux on it, and it had a good quality CRT that you would otherwise have to pay a fair amount for. I did that in the late 90s and early 2000s with a SPARCstation 2 starting when I was in university. (I actually submitted a floating-point-emulation patch to the Linux kernel because otherwise the X server had a habit of crashing when it encountered a denormal number...) However, a couple of things made them fall out of that "vintage but still useful" bracket:

- they fell off the bottom of the "supported by Linux distros" list, so you were running something that wasn't getting security or bug fix updates any more

- LCD monitors got better and cheaper, so running a big 19 or 21 inch trinitron CRT was no longer the best available graphics experience

- at least for me personally, my disposable income for buying nice monitors went up ;-)

Machines in the "are you running a private museum collection" category are less exciting. My SS2 ended up in in the skip when I had to do a house move, I think.