I was watching people tweet positively about rereading Invincible now that it's ended, and I gave up on that series probably around the midway point, so I decided to reinvestigate it too and that series is actually way more flawed than I even remembered.
First, just keep this letter response from Kirkman in mind for everything else that comes up. Funny how this talking point hasn't changed at all in 15 years. 
I remembered Kirkman's pseudo-catchphrase of "This is so gay" being pretty gross even when I was reading the comic as it came out in 2003, while I was in high school. I went to school in both Houston and Seattle and this wasn't a common teen thing in either.
The "this is so gay" stuff from Kirkman is clearly something he thought was really funny, because he inserts it into so many moments it doesn't fit in at all, like this
Invincible wasn't alone here. Gay panic humor was really big with Image creators at this time. Here's the Luna Bros getting in on it with a remarkably bad Invincible pin-up
At first, I thought maybe the "this is so gay" schtick was a post-40 Year Old Virgin thing, because that really did bring back that kind of talk for a while, especially with men of Kirkman's generation, but Invincible predated that by a couple years.
But where the "this is just dated, it wasn't malicious or symbolic of deeper bigotry" argument goes out the window is Kirkman's writing of people of color, particularly non-superhero characters.
There's a relatively early issue where aliens invade the earth and Kirkman represents every person of color-- except for a dimension hopping superhero-- as looters.
That culminates in Invincible catching a black character with powers looting a jewelry store, then lectures him on responsibility until the character sees the error of his ways and becomes "good"
I'm not here to go super in-depth with the failures of a comic that started 15 years ago, I'm mostly just interested in why we pretend like this kind of stuff isn't in these comics when we reexamine them once they end.
Especially because the specific issues here with Kirkman's writing in Invincible have become heightened in our current era, particularly with people like Kirkman, who state they don't want comics ruined by politics but then dehumanize people like this.
Personally, I think an exploration of how these "dated" elements of Kirkman's script in Invincible aren't actually dated because we're fighting these representation battles even harder than before would be more useful than a non-critical celebration of Invincible's run.
