PS4 could not play PS3 games. So a remaster made sense. PS5 will play PS4 games just fine. Are we really signing up to rebuy games on PS5 than can easily be patched? If you want to charge for the UHD patch fine but there is no way we should be supporting $60 remaster of 6 month old games.
If it adds enough improvements and multiplayer I could see it being worth it.
Especially if you didn't own a PS4.