At least now, thanks to modern technology , more can see the art then ever before :-)
Additionally, a lot of the art in the archive is by nature going to be stuff that might make sense to display in a dedicated exhibit, but less so in a general museum. By that, I mean that if you have a handful of Picasso canvases, along with 100 of his sketches, displaying all 100 sketches probably doesn't make sense unless you're doing a special Picasso exhibit.
In this way, the archive is important, and Rijks burning down would suck. Along the lines of your thinking, however, there is a ton of amazing art sitting in investors' basements and shipping containers that we might never see again, much of which we've already lost track of.
Art isn't only something that can be revered. Works of art are basically historical documents that contain a narrative of that period. It's not all self-portraits of people missing an ear or reclining nudes, even though they too contain a lot of information that is telling of the period they were made in. Up until some two hundred years ago artists like painters and sculptors, were some of the few that could actually immortalize, or at least significantly prolong the normal lifespan of people, things or events.
I encourage anyone to take some time to go through these online collections. It's amazing what you'll learn about history by being inquisitive about the subject matter. I can also recommend the Arts & Culture project by Google, which already indexed a tremendous amount of the Rijksmuseum's catalogue.
While I will be the first to agree with you that paintings and other visual art is precious and worth keeping, it is not on the same level as books and knowledge. Comparing these is not doing justice to either one.
Who says there won't be many more museums in 50 years? Or some other model which will result in more art being on display.
If Dutch culture budget gets in serious issues, they could finance museum survival also via sales of those.
The options what to do with it are almost endless and much better than just losing them.
Reason: you won’t find it (it’s in the Mauritshuis in The Hague. https://www.mauritshuis.nl/nl-nl/)