"For many centuries in the Western tradition, how well you expressed a position corresponded closely to the credibility of your argument. Rhetorical styles might vary from the spartan to the baroque, but style itself was never a matter of indifference. And “style” was not just a well-turned sentence: poor expression belied poor thought. Confused words suggested confused ideas at best, dissimulation at worst."
That's Tony Judt over at the NYRB blog. It's a point of view I happen to wholeheartedly agree with, if only because empirical observation proves it to be true. People who write badly think badly. Every now and then I'll grit my teeth and try to read something that's ungrammatical and badly structured because what it says might be 'important' (for a particularly egregious recent example, see here), and almost without exception the piece in question will turn out to be illogical, incoherent or just plain silly.
(This doesn't work in reverse, of course. The most exquisite prose may make no sense whatsoever).
I think the point is that lucid writing is a byproduct of a process of careful thought. The more deeply you think about an issue, the more word choices start to matter, the clearer the purpose of each phrase and each sentence becomes, and the more the sentences themselves fall into a natural order. Clarity of thought produces clarity of writing.
It's a standard too few people seem to care about.