Just because it’s 50 years old doesn’t mean that it has a history that dictates being preserved the way Disneyland’s is.
I am WDW goer through and through. I only visited DL for the first time in my life this year. I don’t say this as a DL local who hates WDW.
Disneyland is the park that not just started it all, it is the park that started modern theme parks as we know them. It is the park that all other massive theme parks owe their lives to. It is the park whose design has influenced every Disney park to follow and even ones that aren’t Disney parks. It is the place where the impossible became possible and entertainment changed forever.
Magic Kingdom is not that park.
Magic Kingdom is a little sibling that has struggled its whole life to live up to its older sibling. It was a park that was put into doubt and disarray when Walt died and the people he left behind were unprepared to take it where he maybe would have.
In the timeline where Walt lived, Magic Kingdom is maybe on par or even better than Disneyland. That timeline isn’t this one. It is an inferior park that has struggled for decades to completely escape the shadow of the park that it was modeled after. The best thing they can do for Magic Kingdom is attempt to give it an identity of it’s own rather than being the lesser form the original Disneyland.
Disnseyland deserves it’s preservation because it has earned it. It is living, breathing history. Would we be talking the same way about Magic Kingdom if it weren’t the most visited theme park in the world? Would would be talking about it the same way if say Tokyo Disneyland opened second instead of Magic Kingdom? I don’t think so.
Bigger does not always mean it is worthy of more than the smaller counterpart. Frozen is a much, much, much more successful movie than Snow White and the Seven Dwarfs, but should we then say that Frozen is a more important thing to keep preserved and remembered than Snow White?