Most of it is nostalgia, and people just don't like to admit it, so they try to come up with complex arguments on why a movie is objectively better rather than them just liking it more.
'89 is the one you identify with most. It's the one you saw first and probably liked a lot.
But to call TDK bad is just..... what?? I understand if you don't like something, but people have to stop calling something bad just because they didn't enjoy it when objectively it happens to be the most praised thing in its category of all time.
It's a good movie, but not a good *Batman* film and isn't really what I would call a good superhero "genre" film either. 89 and the MCU stuff gets things I mentioned right that Nolan doesn't address or doesn't care to. Batman is not a realistic premise and the more you try to ground it the less it works.
And to your "nostalgia" claim, it falls apart when you consider that Superman II is the first Superman film I saw, but I prefer "Man of Steel" as a film (though neither are perfect and MoS has serious issues).
Likewise the Raimi Spider-Man was the first one I saw, but Homecoming is CLEARLY superior to it. Xmen (2000) was the first X-film, but Logan and Deadpool blow it out of the water.
It's not what's "first" but what's better. Smart viewers can make decisions about what's good and what isn't without being led around by the nose by nostalgia.
'89 is cool for its time, but it hasn't aged well at all. The set design is outdated, the effects are outdated, the fight choreography is outdated and bland, and the costume designs are outdated too. If two men in both costumes walked up to me, I'd be infinitely more suspicious of the man in the Bale costume than I would be of someone in the Keaton costume.
This sounds like personal complaints that it's not your preference, rather than being "objectively bad." The "set design" being outdated is also nonsense- gotham of 89 is intentionally retro and THAT asethetic definitely holds up. The "effects" are also practical and almost without exception still hold up- we're not talking about late 90s CGI here.
The only Marvel movie that I would put in the same category of TDK would be The Winter Soldier. Everything from the character development, to the themes and stakes, and overall experience is the only thing comparable in the MCU to TDK.
That speaks to your specific preference for gritty, realistic crime thrillers, but this is NOT a common approach for superhero films- it won't work for most of them and BARELY works for Nolan's Batman. Audiences seem to disagree with you here if box office gross and ticket sales is anything to go by- these are at a very basic level fantastic films that should be fun and encourage suspension of disbelief. Audiences are resonating more with these films than they are what Nolan and Snyder tried to do with the DC properties.
And even if we ignore that, the MCU films are the current standard for the genre going forward and have been since Avengers blew up. NO ONE is attempting to ape Nolan's approach for films within the genre anymore and there is a very, very good reason for this. Without Ledger carrying that movie it's decent but unremarkable- much like TDKR.