Of course all of these games ought to still be preserved somehow, and I don't think they're saying it's somehow a good thing for them to be shut down.

But you asked why some people are okay with it, and they gave you a valid answer to your question. There is a distinction to be drawn between games that had a legitimate reason to be always online versus games that don't, and that distinction is the reason why some people are okay with it.

For MMO players, most of them understand that these are always going to be ephemeral experiences, this is inherent to the genre. It's even baked into the way that many of them rely on subscription fees rather than a purchase.

The real tragedy with MMOs is that even if servers were to stay up, the playerbase may not, so the game will never be the same if the MMO simply drops to MO. Usually by the time the plug gets pulled, it's because the game had already faded away from what it once was.