Rudeness is a means to attract attention, assert power, cover-up ineptitude, deflect personal insecurities, and intimidate meeker people.

A person who holds strong convictions might appear inflexible, impolite, or exceptionally obtuse, when they are merely direct.

You've just inherited rudeness. We've had to work at it.

Arrogance and rudeness are training wheels on the bicycle of life, for weak people who cannot keep their balance without them.

I don't mean to be rude—" he began, in a tone that threatened rudeness in every syllable.
"Yet, sadly, accidental rudeness occurs alarmingly often," Dumbledore finished the sentence gravely.

...William wondered why he always disliked people who said 'no offense meant.' Maybe it was because they found it easier to to say 'no offense meant' than actually to refrain from giving offense.