But that context is something that exists whether or not the original is in front of you. It's something captured in a book about art history, not in the painting itself.
I can understand a collector wanting originals. But why does a museum need originals, now that the technology exists to faithfully reproduce the originals? Why not just sell all the works and put up reproductions? If the point is to teach the public about art and its history, you don't need the actual art there (which has probably been restored five times by then anyway, or, if not, has aged to the point that its appearance no longer matches the artist's original intent); you just need an excellent diorama.
So if the integrity of the work is at stake, it's definitely something that might be done. But museum visitors are kinda like collectors but with less money: they want to see the real thing, not some cheap replica they could buy to put in their home.
Museums don't exist only to teach about art and its history, they exist for people who want the experience of seeing the real thing without being millionaires. Even though most people wouldn't see the difference between the original and the replica and would be subject to some sort of placebo effect if they think the replicas are the originals.