The shift in its meaning is dramatic, but so is the shift in the meaning of "nice", and no one is arguing that we try to turn back that tide. Question:
It looks to me like two principles are at work here. The first is the hyperbolic 'extrapolation' of a term to the limit of its category. The second is the shift toward opposite meaning. Are these recognized etymological principles? I seem to remember a professor of linguistics at Konstanz discussing the second of these. He went so far as to say it could be applied not only to meaning, but to orthography. His example was "amor" and "Roma."
"Decimate" would be an example of the first, i.e., an 'extrapolation' from partial to complete; while "nice" would be an example of the second, i.e., a migration from 'foolish' to 'fitting,' or 'correct' (admittedly these meanings co-exist with more derogatory ones).
(Interrogative (and highly questionable)) speculation:
Webster's online gives a second definition of "decimate" - "to exact a tax of 10 percent from" [that is, "to tithe"] and gives as example, <poor as a decimated Cavalier -- John Dryden>. The shift from 10 percent to ruin here is plausible. The shift from a 'tithe of dead' to out-and-out slaughter of the meaning being discussed on this thread is not similarly intuitive, but maybe it follows a parallel course?
Let's say the contemporary use of "decimated" is a corruption only insofar as one might need a term for a 10% slaughter. On the other hand, the contemporary use might be something altogether new. Is it possible that by juxtaposing the injurious 10% with the ruinous 100% within the term, the word's meaning shifts from "acceptable loss" to devastation? The new term contains not just the notion of what the event (the decimation) ought to be, but its transcendence. By inscribing the word with the image of its own transcendence, does hyperbole force the word beyond its limits and produce something new, and signifying something more than it might otherwise have done?
