Age is completely irrelevant. The purpose of a remaster is and always has been to take advantage of newer hardware. The difference in hardware, in and of itself, justifies a remaster. There is a huge difference mechanically in the gameplay between Zero Dawn and Forbidden West. I haven’t played the PS5 version of the Last of Us, but I’m assuming it’s the same.

The games were held back significantly by the hardware, and because they’re done with modern tooling, they can be done a lot more easily than older games, allowing them to pass the savings on by giving you a cheap upgrade if you own it. They’re nothing projects, and aren’t holding back other projects.