To be fair, this seems like one of those things you either look at and you love it or you just don't get it, but it actually isn't. Just about anyone who grew up with a game controller in their hand and has even the smallest spark of nostalgia for that time period will love the idea before they even finish reading the title.
But, really it is about a lot more. Programming is actually an excellent career, and because kids love video games usually, and the museum teaches them basic game programming, it is really a gate way into higher education. They might take to the art side of it and decide they want to learn photoshop and graphic design, or they might decide they want to make programs for a living or android applications. There are several paths the children can take from there. It may not be a path for everyone, but I don't think anyone has ever said that the world has too many educational opportunities for youths. So if you don't get why someone would want to collect this stuff (which I have a small retro video game collection myself), you can probably see it from that point of view.