Bzzzzt! Wrong answer! Thank you for playing! My NeXTSTEP box was my main dev machine from 1989-1998, even though I had more powerful boxes. Afterwards it move to a secondary role until roughly 1999-2000. In that entire time I had exactly one OS crash, which was due to me setting an invalid parameter. I’ve never had an OS/hardware pair that reliable. The “cool” thing about it in 1988 was the fact that it is a microkernel, so hot deployment of kernel level software and a crash in ring-0 code doesn’t bring the whole OS down. Not that I’m in the microkernel rule, monolithic kernels suck camp. Hybrid solutions are the best solution IHMO. Beyond the kernel level there is a long list of cool features that made it a very productive machine, esp for rapid prototyping.
As for it being a “dummied” down version of OpenBSD, that would be a neat trick, since it wasn’t released for another 8 years. If fact (if memory serves, too lazy to check wikipedia), no free version of BSD exisited at the time. Also, BSD is the poster child of monolithic kernels. And yeah, OS X is derived from NeXTSTEP, but what was cool is '88 is “meh” in 2001.