Actually, I think the reason they did succeed is because they *are* collectors items. Before the NES Mini, the retro consoles were mostly third party made, mostly mediocre or low quality, and mostly a 1:1 ratio with the bulky systems they replicated. And they sold passably.
Nintendo comes along and uses miniaturization to make a device that is not only functional at a higher quality than those previous retro copies, but at the size, can serve as a display piece when you're done using it. And, after Nintendo was taken off-guard by how successful it was given the middling success of other retro copy consoles, the rush to copycat ensued. Leading, ultimately, to Sony. And given the game list, the purpose of the PS1 mini is to play the one game you loved from that system, then display it as a collectors item.
