In my other answers to @grimjim's post I already shared my opinions to most of your points, which in the end aren't that different (X-Card abusers, conventions, not trying to be the guy making someone cry at your table, …)
However
I've always found of the X-Card to be a tacit admission that those people most invested in calling for one don't see the other people at the table as people worth talking to, nor do they see them as people who have responsibilities for themselves.
Summarizes the whole X-Card-debate pretty well:
The X-Card should not replace proper communication, but the X-Card is (or should be) a shorthand for everyone to say (especially to the currently talking person)
"I do not want the thing that is happening right now. Are you all alright with changing/skipping the narrative, or should I explain myself for a second?"
It should then be everyone else evaluating "Am I alright with nodding this off, or does this spoil my fun, in which case I should talk about this."
Often however some people say "If someone raises the X-Card the current thing HAS to be skipped, no questions asked!" which doesn't talk about the problem, not solving it. The whole RPG is a conversation, people should talk about it.
If someone isn't happy you should talk about it.
Don't forget to talk about stuff. Talk about why you used the X-Card. Talk about how you intend to carry the game on. Talk about the other players opinions.
Talking about things is often forgotten when talking about the X-Card.
The problem from where I sit is that "the X Card should not replace proper communication" is what a lot of people *say,( but when you look at what they actually do – it's not a shorthand, it's the only hand.
Why do you need shorthand for a two second act? Seriously. A reasonable adult should be able to hold up their hand, point at the GM, and say "hold up, I'm uncomfortable with this," or point at someone else at the table and say the same thing. Then they can have a discussion.
Unfortunately, this gets coupled with "anyone that's uncomfortable should never have to explain themselves," which is a toxic combination. That idea is toxic to communication in general, anyway, but in combination with a clearly defined trump card (irony utterly intended) it actively impedes the conversation at the table.
I much prefer to disengage the whole thing up front. If I wanted to run a game for kindergartners, I know where the local schools are. Of course, the local kindergartners generally have a better grasp on how to play together that a lot of adults, especially in the RPG industry.
The shortcut shortcuts conversation. It actively impedes communication. Especially in combination with a lot of the other rhetoric which comes out of the mouths of the people who espouse the X Card, it's actively pernicious and damaging.
Screw that. I don't need that kind of static.