Geoffrey K. Pullum is continuing his crusade against the idiocy of Strunk and White's The Elements of Style, which celebrated its 51st anniversary on the 16th of April. More power to him, too; if I'm ever feeling sad, all I have to do is turn to the section on passives and read the "examples" for a hearty laugh at the kind of incompetence that presents "It was not long before she was very sorry that she had said what she had" as an example of a passive sentence.
Being the sort of child who read grammar books for fun, I never had much cause to refer to Elements. I think I have a copy in one of my bookshelves somewhere, but (thank the Lord!) its grammatical inanities never found their way into my consciousness. I therefore employ adjectives and adverbs with wild abandon, adore long and complex sentences, and generally have some writing habits that would probably give S&W apoplectic fits, were they not long dead. I'm very happy with this; given that I graduated magna cum laude, I hardly think that the use of adjectives or the length of sentences are really the main issues here.
The problem that faces many college students is the need for an intuition about what makes good writing. Since I've recently re-read Walter Ong's Orality and Literacy, I've been thinking about the difference between spoken and written language. Every normal human being (i.e. having not suffered serious emotional or physical trauma or mental deficiencies) learns not only the grammatical structures and vocabulary of their native language but how to utilize their linguistic knowledge in various social situations. In other words, native speakers have intuitions about how to use their language skills in various situations, with different people. They know which words are taboo and which are generally appropriate for a certain purpose with a certain person, although they may choose to ignore convention or intuition for a particular effect. This skill is just as important and intrinsic as syntactic, morphological, or phonological knowledge and intuition. Naturally, given the differing talents and intuitions regarding interpersonal relationships, some speakers are more adept and successful than others, but barring mental disability or other psychological factors, everyone can generally do it.
The key to writing well is to cultivate a similar intuition about written language. The considerations are similar, or at least parallel in many cases: Who is the audience? What are they expecting to hear? What do they want to hear? What kind of language is appropriate? As with spoken communication, the skill and success of each writer will differ, but unlike with speech, there's no guarantee that any given writer will ever be able to do this well. This is because speech is extremely natural, intrinsic to what it means to be human, whereas writing is a convention and a tool, not a natural part of human cognition. Speech comes naturally; writing has to be learned. And in the same way, the dynamics of interpersonal speech communication develops naturally, but the dynamics of written communication has to be tediously and meticulously learned. Of course, it comes easier to some than to others.
The goal of language/grammar books such as Elements is not to teach students how to compose language (usually), as, given the fact that they are usually native or near-native speakers in secondary education or above, they already know how to use their own language faculties. Instead, Elements is focused on "style", which in this case seems to mean "the proper application of spoken language faculties to a written medium." As Ong suggests, the style, form, and even cognition processes involved in writing are very different from those of speech.
The problem is that, just how what is accepted and standard in spoken language fluctuates frequently, what is acceptable and standard in written language changes as well. Even if Elements was accurate at the time it was written, there's no reason to assume that the same protocols apply; written conventions fluctuate just like spoken conventions do, although certainly much more slowly and reluctantly.
So how to teachers teach students to write clearly and beautifully, especially in an age of txt msgs, truncated RSS feeds, and Twitter? I don't have a catch-all answer, but I'd start by doing the same thing students have been doing for millennia: observing the masters at work and emulating them. These students know how English works, but just like they need to learn some conventions when meeting the President or their in-laws, they also need to learn what is appropriate and encouraged in writing as well. And really, outlawing passives and adverbs is not going to help.