Mandatory in what sense? You can say all the same things VoR does, point and laugh at anyone you see whom you think might be trans, etc., and not get into any sort of legal trouble in any country I know of.
"Politeness and decency" may be becoming socially mandatory, in the sense that if you say certain kinds of things then many people will think you're a bigot, but that's hardly a new phenomenon -- though of course the details shift over time; e.g., it's more acceptable than it used to be to be rude about Christians and less acceptable than it used to be to be rude about gay people.
Mandatory in what sense
Both in this sense and in this as well.
that's hardly a new phenomenon
Of course not. Intolerance is a perennial feature of human societies :-/
There are some long lists of false beliefs that programmers hold. isn't because programmers are especially likely to be more wrong than anyone else, it's just that programming offers a better opportunity than most people get to find out how incomplete their model of the world is.
I'm posting about this here, not just because this information has a decent chance of being both entertaining and useful, but because LWers try to figure things out from relatively simple principles-- who knows what simplifying assumptions might be tripping us up?
The classic (and I think the first) was about names. There have been a few more lists created since then.
Time. And time zones. Crowd-sourced time errors.
Addresses. Possibly more about addresses. I haven't compared the lists.
Gender. This is so short I assume it's seriously incomplete.
Networks. Weirdly, there is no list of falsehoods programmers believe about html (or at least a fast search didn't turn anything up). Don't trust the words in the url.
Distributed computing Build systems.
Poem about character conversion.
I got started on the subject because of this about testing your code, which was posted by Andrew Ducker.