I used to work at Cycorp, a holdover from the AI world of the 80s and to this day a classical (CL-like) Lisp shop. They have an old Symbolics box in their entryway, positioned by a couch as a small coffee table :)

I find the whole idea of hardware that's specifically optimized for a totally different programming paradigm than what we're used to just fascinating. It's not hard to imagine why we haven't seen more of it: it's really expensive to iterate on a branch in the computing hardware tree, and you're probably better off just writing a runtime for mainline systems. But still, it's fun to think about.

I am a little surprised though that nobody's written an operating system like this for standard hardware. Still a big task, but an order of magnitude less ambitious than custom hardware and with many of the benefits people would've gotten from a Lisp machine.