Emulation is one thing but retro gamers often want to play the real thing. That's my favorite way to do it but I am not capable of keeping a retro machine running. Modern PC gaming has spoiled me compared to the work it often used to take getting games running back in the 90's. Otherwise I would say that for a huge percentage of retro gamers, building and upkeeping your own personal retro computer was part of the experience, which is why I think that there was very little interest in a pre-built box.
"The assumption that animals are without rights, and the illusion that our treatment of them has no moral significance, is a positively outrageous example of Western crudity and barbarity. Universal compassion is the only guarantee of morality."