> The Microsoft Word grammar checker REALLY hates it (although it's moronic anyway) and will suggest an active alternative to every single passive sentence.

That's absurd. I hope you can toggle that on or off? In certain kinds of documents, it's a REALLY good idea to avoid the passive voice, but that's an issue of style, not grammar. It's perfectly good and proper English.

> I happen to like the passive voice, and I don't think it makes the language weaker, as such.

It really does, even if it's just on a subconscious level. "He was insulted by Stephen" means exactly the same thing as "Stephen insulted him," but the latter has a bluntness that drives the point home more sharply even if it doesn't particularly drive it home any more surely.

Sometimes, as you say, it's necessary, particularly if the subject is either unknown or better left unstated. And sometimes you *want* to state things weakly. "Weak" doesn't mean "bad." Just like "pompous" doesn't mean "bad." The passive voice, as well as the pronoun "one," have their place in English. Whether you use them or their alternatives depends entirely on the options available to you in any given situation and what mood, tact, connotation, etc, you wish to convey along with the meaning.