Yes, this is just a normal part of social register shift.

cripple and impotent (outside of medical environments), bugger (in America), arse (in America), cur, stooge, mook, "what a plague...?" (used like "what the hell...?")

I chose a number of examples from different types of stylistic shifts.

• Archaicisms: "What a plague...?" was archaic even in Shakespeare's day, cur is softened because it's recently become archaic, and mook because it's nearly archaic, and stooge because it's just starting on the path. This is the most common route.

• Social Shift: Cripple and impotency used to be strongly inappropriate unless you were stating a medical fact about someone, but now the two are no longer insults. This is due to a social change. The inability to walk or reproduce, while still undesirable, draw sympathy rather than disdain. The older way of thinking was to curse your rival with medical ailments; now it's strictly unfashionable to do so.

• Dialect Diversity (1): Sometimes a particular dialect in a language will lose the active meaning, and only passively utilizes the word - and thus it seems foreign and neutral (bugger in America).

• Dialect Diversity (2): Sometimes one dialect will soften the taboo while another will not (arse in America).