Yes, you are correct about about not being able to upgrade from PS4 Spiderman to Remaster.
But people saying it should be free are dumb.
Its a Remaster, since when remasters are free?
I don't see Microsoft calling any of those free upgrades Remaster, but i could be wrong.
Here comes my train of thought about the whole Spider Man Remake shitstorm!
There are a few things added up that makes such a negative impact:
1. Sony said multiple times how BC is important for them and stated that they will update the PS4 games for PS5 increasing their performance.
2. Their whole BC explanation is really poor - they said about Ps4/PS4 Pro mode/Legacy etc. but without much of a details - can we expect 60fps/4k? Can we expect combined performance/resolution modes from PS4 Pro? They also said really important statement - at the minimum the game from PS4 will work the same on PS5 but any additional upgrades is up to developers. So any kind of upgrades of PS4 games for PS5 is dependend on a good will of a dev.
3. Microsoft comes with it's Smart Delivery - and in fact they showed Gears of War 5 and how it is upgraded for Series X where it goes above PC max settings. The diffrences are visible but not something really mindblowing. I would not call it remaster (but still it is some kind of remastering of the X1 version) -
4. In the meantime MS Smart Delivery info caused a lot of dev to ride the "good pr of MS" and annaunced upgrades for PS5 - like Cyberpunk and Assassins Creed Valhalla and some more titles I can't remember right now.
5. long-ass period of now info from sony and many of players alread took for granted that BC upgrade is something that we will get from Sony because If MS gives them why would Sony not if they were the "good guys" at current gen.
6. Info about Spider-Man Remaster not avaible for free for PS4 version owners drops. And here comes the problem - they did not show us how big changes are. This will backfire either way - some expect it to be similiar to Gears of War 5 and if MS does not want additional pay why would Sony want? Other people claims it is full remaster and expects full-power PS5 graphic. If Sony does not deliver it there will be in even more dire situation than now. Now back to point 2. - Sony statamets simplified - Good devs will upgrade games, bad devs will not. And everyone considering Sony the "good guys" expects them to somehow (similiar to how MS upgraded GOW) upgrade the PS5 version of PS4 game and charging additional fees for remaster is contradictory to what sony made us to believe - that they are a good guys that will do all they can to upgrade PS4 games on PS5.
IMO it all comes to the lack of fucking informations from Sony. How BC works? How the remaster will look like? On top of that MS pr moves a few weeks back gave players a time to get used to how upgrades will work and some kind of "vision" about how next gen will look and what can be expected.
I think it all comes from Microsoft. If Sony would stated it earlier this would have way weaker (negative) impact. And Microsoft indeed are giving upgrades but they are not calling them Remasters. It is confirmed that Gears of War 5 will have higher settingh than those avaible on PC.