First of all: thank you for taking the time to write such a lengthy and thought-provoking piece.
The bad news is you have touched on so much I would like to comment on and pull apart a little I scarcely know where to begin so please forgive the length of this reply!
I am precisely who you were hoping to reach, ie the older gamer (Is 39 old?) and I agree with a lot of what you are saying.
I will start by touching on the GOAT scenario: I don't think Ocarina of Time is still lauded as the goat for how it compares to modern gaming or that we haven't produced anything better in 25 years. Rather it is the impact it had on its release for solving some of the great design problems of moving games into 3D. Action/Adventure titles have improved upon its mechanics in so many ways since 1998 but strip away all those things and you find Ocarina of Time at the very core, from lock-on mechanics to insignificant things like the sheathing of weapons onto the heroes' back.
For the record I think Legacy of Kain: Soul Reaver from 1999 is a much better title. Have you played it? It has a shakespearean-level plot, a game world that streams seamlessly from the disk eliminating load times, the dual-world mechanic from Link to the Past taken up a notch by letting the player morph in real time from one plane of reality to another and the same tricksy dungeons and satisfying combat from Ocarina. It also did this on the PS1, a technically inferior machine to the N64.
As for modern gaming, I don't think it comes down to despair for the future of software but rather for the players themselves. Games are designed now to maximise player engagement over years. There is nothing inherently wrong with this: I have been playing Fortnite on a weekly basis with my other senior-gamer chums for years now. But I look at my oldest son, now aged 15. Like many players his age all he plays are long-term titles like Fortnite and Rocket League. Nothing wrong with these very-good games but this is often at the expense of experiencing the wider palette of software gaming has to offer. I hate to be an 'in-my-day' person but when I was 15 (in 1998) you'd finish one game and move onto the next one and experience a swathe of different titles as you swapped and traded with friends.
By playing only a few games to tremendous depths there is a whole generation of players missing out on the joys of a wider gaming market. This is where our despair comes from. Games are as good as they have ever been but there are less players getting to experience them and this is a tragedy. We also have an industry that is not engaged in game preservation and it remains either hideously expensive or illegal to pursue the titles of yesteryear. These games weren't better than what we have today but it is crucial that with a medium that has the ability to store itself as data indefinitely new players can see where their favourite games evolved from and how crappy some older titles were!
We older gamers often have limited time to explore new titles as we have families, jobs etc and as a result probably do complain about the length of some modern titles because we don't have the time to invest in them that we would like whilst also being able to experience the swathe of titles we do so love. I had to purposefully sell Horizon Forbidden West once I had done the story because I just do not have the time to complete all the sidequests.
GOAT lists are often based on opinion rather than a weight of facts. I for example would regard Super Nintendo classic Secret of Mana as my favourite game of all time. I base this on its colourful graphics, memorable soundtrack and the fact my best friend and I spent the whole of the summer of 1994 playing through it. But I also recognise its shortcomings like the terrible script and lack of sidequests. I would actually regard Tetris as the GOAT simply because it is a game anyone can pick up and play, it remains fun each and every time and it hasn't aged a day in 30 years. It is the videogame equivalent of Chess. I'd be interested to know what your favourite game of all time is :)
Note 1: I thought FFXII sucked as well. For me it was the lack of outfit changes with the jobs. There is no way Vaan would not freeze to death in that waistcoat on the frozen tundra.
Note 2: I did like FFXV though. Accidental as it may have been, I liked how the game got narrower in scope as you got towards the end of the game, leaving you to the sidequests whilst on your bachelor party at the start rather than having to take a 2-month vacation during the impending apocalypse to try your hand at breeding giant chickens.
Note 3: You can find me and a whole enclave of older gamers over on the fringes of what is left of Web 1.0 at www.grcade.com, a community we have kept going for over 20 years. If you'd ever like to come over and talk shop you would be most welcome. (Me? Username: Carlos)