Most linguists are militantly anti-Strunk, and generally anti-prescriptivist -- they tend to work on the assumption that anything a native speaker would actually say is grammatical. I sympathize with this point of view as a prescription, viz. that anything inoffensive to the ear should be treated as grammatical, but it seems to me that descriptively speaking it's all wrong. Many of the changes in English usage between the 18th cent. and today -- from the standardization of spelling and punctuation to the abbreviation of presidential sentences -- are due to the influence of prescriptive dictionaries and books like Strunk.
Besides, some cultures tend to use diction -- like accents or clothes -- as a class marker, and you can't create e.g. an "upper-class twit" way of speaking without forbidding some "perfectly grammatical" (in the linguists' sense) forms. Since speech isn't entirely conscious, the only way to keep to these rules is to have them drilled into you in early childhood, which is done at home and at expensive schools. The more unnatural and arcane your rules the better they serve their purpose, as this makes it harder for the lower orders to pick them up, and more certain that they'll give themselves away by sliding into natural but "deliciously low" phrasing.
If we want to enforce class distinctions based on birth or education, it seems that arbitrary usage rules are a good way to go about it. A position on arbitrary linguistic rules is therefore a political position; it's beside the point to whine about "bad science," as people at Language Log like to do.