So you LIKE the idea?
your favorite company could not have done this better you mean?
There are 3 options: to give away the new version for free if you bought the old one in a Cross-Buy fashion, to pay a small fee to upgrade or the one Nintendo uses for all their games and was the common one in all the previous generations: having no upgrade option and to pay the full game price again.
I obviously prefer the free upgrade. And if not, the small fee.
Yeah don't need adaptive triggers and etc. But atleast throw a bone and unlock that framerate to 60fps. That's not really putting resources unlocking frame rate. There are hackers who have unlocked framerate on Bloodborne on PS4 Pro, Last Guardian unpatched runs at 60fps. We all know unlocking framerate isn't a big task, but unfortunately these Devs just wanna charge more. Like for example I had no issues with Ghost of Tsushima remaster as they did unlock the framerate for PS4 version so can easily ignore the remaster and extra features.
The amount of work depends on the game. Sometimes the game is very old, and if you try to update anything, the engine updated and doesn't work well generating many crashes, no needs many adaptations of the game to the new engine. And when done profesionally, the updaes or re-releases need to be tested again and to pass a certification process and so on, because it's very common that when you touch something you break something else.
These costs are way smaller when done to update an already existing version compared to release a native version for another console. You don't have to pay age rating, depending on the platform you skip the certification process and the testing is only internal. Plus you don't need to support the new -mandatory- features (in this case for PS5 haptic feedback, adaptative triggers, 3D audio, activity cards, etc).
In addition to don't work for free, quite frequently devs don't update games because they are busy with other projects, the next game they will release. And don't have free time to give you free stuff because they are crunching like motherfuckers.