There is definitely a need for computer museums as they are the keepers of historical artifacts. Without them, a lot of people wouldn't see the more rarer computers and computing artifacts that are just not attainable or even visible in the age we live in. We are in an unusual era where computers are relatively new and anything from 1975 and up is still attainable though there are very rare items one is not likely to attain.
But we are also in a different era than our forefathers who could only see rare historical artifacts in places like a museum. Now adays, as individual owners of some of this "computer history", we have the ability to broadcast to the world via various types of media so sending something to a museum, at this point, does not guarantee that more eyeballs will see it. In fact, as you have a YouTube channel, there is a potential for more people to see the item than in a museum, and I am not talking about the casual observer who walks by something and says, "That's cool", and then keeps walking. Enthusiasts who are seeking out some of these computers have the ability to see items in videos, blog posts, websites, etc. in far more detail than in a museum. They also have the ability to interact with these owners in a way that is unique to an item being in a museum. As vintage computer enthusiasts, we have the ability to put up videos or have web pages, social media posts, etc and make these rare computers even slightly more accessible.
I am personally conflicted about museums. Large museums have the resources to store your items and perhaps put them out on display occasionally but there are just so many Altair 8800s they can accept before they turn people away. Smaller "museums" or public displays have a more enthusiast attitude but the longevity of the items remaining in a historical collection may be in jeopardy over time. Consider the "Personal Computer Museum" in Brantford where the owner passed away. I think parts of it were sold off and I don't know what happened in the end but stuff like this happens so one doesn't know if a smaller public collection like this is the right answer.
I am particularly sore about the wooden PET that was "found" in a museum after much searching. It was mis-catalogued and computer enthusiasts had to go find it. When they did find it, two of the original engineers had very restricted access and when asked to be able to display it at a computer show, the request was denied. Now, I get that it is a one-of-a-kind item but as far as I know, it's still in storage and the only signs that anyone knows it's still existing is because Leonard Tramiel and John Feagan's were allowed to see it and they took some pictures. That said, I was not there to know specifics on access as I only heard about it but I know that many Commodore enthusiasts would pay to see it if the prototype wooden PET was a display all by itself.
When one considers survivorship, if you're ready to "lock it up" for histories sake, and a reputable museum is willing to take it, a museum is a good place. However, while other enthusiasts still have these computers in their collections, it might not be time for that just yet. I've personally lent things out for shows, taken specific pictures for people who are working on a restoration, ran and recorded video of a computer to confirm an emulator was running true to the actual hardware, shared software and firmware, done my own restorations to get something to work, etc. I've also given up a few parts to people who had a need for them so they could repair their computers. I've also reached out to other owners for information or pictures myself, when needed. Unfortunately, all of this stuff pretty much ends when it hits a museum.
There are good things and bad things as you mentioned in your OP. One just needs to consider what is given up if/when something is donated to a computer museum.