I agree with OP and there are a few considerations I'd like to make here.
First of all reboots and modern sequels are kind of a thing of their own since they are burdened with their predecessors' legacy which is rather hard to live up to.
On the OP: I still have to play the new Wolfensteins but based on what I have seen they completely altered the original games' spirit.
Then there's the matter of the discrepancy in development focus (which I agree with): back then the games were essentially gameplay driven while modern ones are mostly aesthetics driven instead: the horsepower needed wasn't there to support the graphic fidelity we have been used to in later years.
They were trying to make up for it with gameplay and by luring gamers with side contents in the form of printed lore-expanding media and booklets and concept art, also, game boxes were incredibly appealing and well made.
I don't see it as a modern phenomenon but as a precess instead going on since ever basically, I guess, through the 90s and up to today where we've reached the point where coding gameplay mechanics and making assets is cheaper than spending millions in motion capture/performace capture material.
Clearly modern/casual gamers are used to other types of media and ask that.
Conversely shooters from the past have very basic mechanics which developers made up for with clever workarounds, fun gameplay, good stories, and, again, the power and media, holding the games, where not always there to support their needs.
Just think of DooM: it wasn't possible to stack rooms on top of each other, they had to compensate with satisfying shooting, fast action, speed of movement and larger levels due to limitations of the engine which then became the id Tech 2, Quake Engine: geometry became incredibly complex compared to the past but levels became smaller at the same time and they had to slow down the character because otherwise they felt small.
Unreal is a great title, the look of it, the AI were something nobody had seen before, I remeber being astonished seeing the Skaarjs dodge my rockets and ASDM shots, at the same time, though, the game suffers of the same problem of the games of the age: the bullet sponginess of the enemies.
All he games from that time have enemies that you have to unload a chunk of ammo of the effestive weapon to take them down and, again, Unreal was the only one that enemies behaved life-like or at least credibly.
To be honest Unreal focused both on single and multi player and was the first game that let you train in MP with BOTS without the need to resor to mods.
Good games and crappy games always exjsted but I think that the single player games peaked in the 90s on average, I mean, back then the points of reference were, DooM, Heretic, Hexen, RotT, SS, DooM, Quake just to cite a few of the biggest titles which many other were clones of which in many cases delivered, today what are the titles publishers and developers are looking at?
To me they destroyed and are still actively butchering (System Shock Remake) so many great titles that I can't even think of it without feeling sad and depressed.
I am going to stop here for now, might keep on later on.