I think you're missing the point. Museums collect this stuff not because it's old, but because it was significant to people at the time and they want to collect it for prosperity. Imagine if they waited until 2050 and then said "Shit! Wasn't there a cd player we all liked at some point? Does anyone have one?" They should have one, they're a museum! Many museums will be maintaining an iPhone collection for example.

Regardless, most people under 30 likely do not have access to a cd player, and I'd guess many never owned one. It's not strange for that to be in a museum even without what I've said above.