It's not about a kiss. It's about promises made by the narrative that were never delivered.
The reason the fandom is reacting this way is because Neil Gaiman changed the genre of Good Omens from adventure fantasy comedy to romance fantasy comedy, and then he broke the cardinal rule of writing romance comedy: There must be a happy ending with no tragedy.
The story stops when the couple feels the most optimistic and hopeful for their future. A tragic ending does not belong in rom-com. It does not belong because going through this emotional journey with the couple only to have it end in painful disaster makes readers angry.
Good Omens S1 introduced overtly romantic elements with scenes that did not exist in the book:
Crowley flirting with Aziraphale as they watched the animals board Noah's ark.
Aziraphale flirting with Crowley in Rome.
Saving Aziraphale's reputation and his books in the church.
"You go too fast for me, Crowley."
"We could run away together."
"I don't even like you / Yes you do."
"Your boyfriend in the dark glasses"
There are tongue-in-cheek implications of romance in the book, but it is never explicitly stated or given space on the page to explore because how Crowley and Aziraphale feel about each other is not the point of this story. The humans are. We spend far more time following the humans and their thoughts and struggles because this story is not about Heaven and Hell, it's about humanity fighting for its right to exist.
To explore Crowley and Aziraphale's relationship in the original text would have made them too important. They were not supposed to kiss, there was not supposed to be a love confession, they were supposed to run around like incompetent headless chickens and make us laugh.
This is why fanfic exists. We pick up on the context clues in the text and we write our own stories to flesh out the things we wish had more time in the canon, even when we understand why it wasn't included.
But Gaiman gave the angel and the demon a whole bunch of extra scenes in the TV series, made their interactions overtly romantic in nature, and it disturbed the balance of the story. Good Omens became about them and their 6,000 year slow-burn enemies-to-friends-to-lovers story arc. Adam and Anathema and Shadwell became moving pieces buzzing around Crowley and Aziraphale.
The building up of Ineffable Husbands diminished the importance of everybody else until they ultimately got sidelined in favor of an outright love story in S2.
It's like the significance of everything the humans did was undone by Ineffable Husbands. This is no longer a story about humanity claiming its sovereignty and choosing their own fate in spite of plans made by Heaven or Hell. It became a story of how the unlikely love between an angel and a demon is the only thing that could possibly save the universe.
No. No, no, no. That was never the story. Could never be the story. Good Omens was never supposed to be a romance with Crowley and Aziraphale at its center.
Imagine When Harry Met Sally but Sally gets hit by a car after their love confession. Imagine The Princess Bride but Prince Humperdink wins. Imagine A Midsummer Night's Dream ending in shambles. That is the level of narrative betrayal happening in this script. That is why people are angry. It's not about a kiss. It's about giving us two seasons of a rom-com and then slipping us a tragedy at the end and calling everyone ungrateful when we rightfully complain because this was always meant to be how it ended.
Which only reveals that Gaiman was planning to betray his audience from the start, because he does not write happy endings.
This is why we are angry. It was never about a kiss. Gaiman broke the rules of rom-com and now we are angry.
