Maybe SSC is long because it's putting forth complex ideas. Ideas that some readers don't want to take the time to understand.
For those who want a few sentences they can chuck into one of the pre-existing boxes they formed at school, I agree SSC isn't very convenient for that.
I thought the article made interesting points, but could have done so far more succinctly. By comparison, when I read Richard Stallman's stuff, I don't always agree with it, but I'm usually impressed by how concisely he is able to say things. SSC is too often the opposite.
Subjective feelings aside, it would be more interesting to give an example of an author who addresses the topics Scott addresses at a similar level of insight and manages to do so more concisely. I don't think Stallman is much of an example of that.
Good writing is not some universal fungible. It really does depend on what you're trying to say. And there are basically no other writers I can think of who are trying to model a way of thinking like Scott.
An analogy: we're mostly experienced programmers here, so we can usually understand a quick description of a programming concept even if it's new to us. A programming book for beginners might have to spend much longer getting the same idea across. Perhaps "Scott's way of doing things from scratch" is like that. But once you've read a few of those essays, you're no longer a beginner, so you'd rather have the quick version.
More than once I've gotten the impression that people who criticize Scott for verbosity assume he's blah blah blahing about stuff they already understand, when in reality he's thinking a couple levels deeper than they're accustomed to from a blog.
Ok, that is a reasonable distillation. And you just said it in one sentence. Why does it take Scott 20 pages?
Scott knows that people will blithely accept his thesis as obvious... until the moment it matters most, when there is social pressure to accept something untrue. He wants you to feel the price you'll pay if you cave.
Most people are not interested in reading a Wiki article on an abstract topic, and want to be taken along for the ride - including why it's worth reading the article.
He is an excellent writer for getting hundreds of thousands of people to want to know about Kolmogorov complicity in a useful way.