Emulators are also valuable here; the work done on bsnes is amazing, and MAME does a pretty solid job of emulating hardware (including old Mac hardware) accurately.
There's also still quite a lot of retro hardware and books for sale through used markets; enough that people make it their (if not particularly lucrative) business to collect and resell 'vintage' hardware.
History tends to filter out the bad ideas, such that many of the best ideas survive today. However, human's cultural filters are not perfect, and there are lots of good ideas and intellectual context that can be exceedingly valuable to understanding how things became the way they are, or demonstrating alternative paths (which may even be better than what we have today) that did not emerge for market, financial, or cultural reasons.
I really find historical technology to be edifying in the same way political, musical, and broader cultural history is edifying. I think it's a shame that we don't spend as much time teaching technology/design history to software engineers as we spend training 6th graders to understand their local political/cultural history.