if take-two would have just released them and made some money for themself none of this would have been necessary
Don't you just hate sour grapes
No. There is still great appeal in a reverse engineered back to source game, ones that will continue to see these made in secret (or be like ROM sites/let's plays where lists of devs and pubs that are accepting/care and those that don't) if this does go wide and decompilation tools get more and more advanced; while they have been somewhat practical for a little while I would have still been wrong on the timeline here and was expecting another few years at least, especially for console based stuff, as most things in decompilation are still more theoretical stuff that is the subject of research phds and them looking more to advance things a bit rather than rock the boat.
The amount of mods you can do vs the baseline what the devs envisioned in the API, and made tools for, even a good one (and there are so very few of those) or hoping some assembly capable hacker* is massive.
*assembly is rarely taught in schools (if you are curious I suggest
https://www.plantation-productions.com/Webster/ https://stuff.pypt.lt/ggt80x86a/asm1.htm and maybe as a more gentle into then
this video series, and what little is will rarely be to be used in anger as much as demonstration of why you don't call a function within a function. Indeed many modern compilers might not even support it (gets in the way of various types of security). Even ignoring all that and magic summoning a decent assembly coder the amount of time such things take vs messing with source code (which can be done by almost anybody for some more basic things;if you find a variable saying draw distance and pump it up in most games it might grind a vintage supercomputer to a halt but given your phone today probably has more power...) is considerable.
I might even go so far as to say number of times games saw assembly hackers step in on PC games since the late 90s when I started following all this to do more than remove anti piracy, remove Windows version checks (they sometimes try to gently encourage people to upgrade for no technical reason), remove multiplayer server checks, occasionally be the ones to make widescreen work, and maybe occasionally search things for evidence of future updates (though most things you see erroneously attributed to "dataminers" on gaming news sites are more someone pressing find strings in a hex editor) is minimal, and indeed I reckon you are more likely to find people using assembly in anger in console game hacks where it is still considered hard but an essential step on the path to becoming good there.
That is also saying little about expanding it beyond its baseline abilities; want a make a world 500 times the size, or maybe streaming, multiplayer, all new graphics... all well within reason where the assembly type might be faced with a nightmare project.
General bug fixing; most mods tend to work within parameters of the game. Remove items, maybe block a way, maybe change some stats, maybe make ammo rare, changing a spawn point... this you are literally controlling the game's code and all that entails.
It also feeds back into more conventional level editing as you literally know how the game works/handles data now.
The ability for glitch searchers, speedrun types, cheat makers, in game animation/machinima types to do their bit with this sort of thing is also massively expanded by having source code to play with/look at/ponder.
Some graphics tweaks already mentioned but higher res, widescreen, ultrawidescreen, multi monitor, odd aspect ratio (maybe you have a 16:10), 3d glasses... go from hacky nasty method (
https://www.wsgf.org/ for many) to glorious and able to fix bugs. Nice new filters also get to be a thing.
Porting to other systems as no financially sane dev will port it to half the things it got ported to.