As someone who has several pet peeves of my own (e.g., "impact" for "affect" and "orientate" for "orient"), I was brought up short by a recent book from David Crystal titled The Fight for English: How Language Pundits Ate, Shot, and Left, written at least in part as a response to Lynn Truss's Eats, Shoots, and Leaves. His primary point is that prescriptive grammar, punctuation, spelling, and pronunciation are constantly changing, indeed have always been changing. (He cites evidence going back a thousand years to Aelfric the Grammarian!) Nothing can (or should) be done to try to stop this change. The rules are not useless, he argues, but they should be understood in context. What is important is how clearly and effectively we communicate, not whether our means of communication is perfectly in accord with the (always changing) rules. Further, the less formal the context of communication, the less we should be concerned about deviations from the rules that do not hinder meaning.
Crystal is one of the world's foremost authorities on the English language. He has written many books, including The Stories of English, a fascinating history of the language. The Fight for English is just as entertaining. I recommend it highly to my Cruciverb colleagues. It might even reduce our stress levels regarding pet peeves just a tad.
A final note: As I proofread my message (and who proofreads any more!?!), I discovered that I had a plural subject and singular verbs in the predicate clause of the sentence beginning "His primary point is . . . ." (I had originally mentioned only grammar and not the other features of language---hence the error.) Crystal would suggest that my error was trivial and unimportant since it is unlikely that it altered or clouded the meaning of my statement. Moreover, I am writing informally, in an on-line discussion forum, which makes the error even less important. Still, I"m sufficiently a "prescriptivist" that I went back and corrected the error!