I just read this PC Gamer piece on flavor text and I wanted to think out a few points around it. I think that people tend to undervalue flavor text and I want to push a bit more against that.
Like seemingly all game design jargon, flavor text is a term that is itself flavorful, but a little inexact. We're used to considering something like the italicized text of Magic: the Gathering cards as flavor text and similarly the quotes in SM:AC are clearly flavor text. So, I'm going to restrict this to in-game descriptions of game pieces. There are definitely other things that I think can be considered analogous, but I'm just here to argue value not taxonomy.
I think that the fact that flavor text is inessential to progression causes people to privilege mechanics over it when considering the relative importance of different parts of a game.
Take Gulliver's Travels as a thought experiment. You can read Gulliver's Travels without engaging with the politics of the story, but instead simply as an adventure tale. This is exactly what I did as a child. However, to privilege the adventure part over the satire would be to lose the entire point of the novel. Similarly, you can play music without ever listening to the words, but have you really heard "Stan" until you follow the narrative?
People can play without engaging with flavor text and some undoubtedly do, but that doesn't devalue the flavor text. It is not necessary for every part of the game to be engaged with by every player.
Having said that, I do think that flavor text has a significant impact on the actual mechanics of playing a game. It can substantially reduce the complexity of a piece by giving the player a bit of a story to help comprehension and by acting as a mnemonic. Additionally, it functions as a reward moment for the player and threading these moments through the game has significant impact.
I take issue with the idea that flavor text is the analogue of spice in cooking. I've eaten a lot of bland food in my life. Sometimes food is just functional and it's okay for it to lack spice and flavor. I want more from games.