|In general terms, I'm in favour of having a high space to text ratio because it's easier on the eye. The extreme example at the threadhead is, admittedly, annoying but I would prefer it to the style many of the trolls prefer where the words are crammed in like the interior monologue of a cokehead.|
The most effective reports I write or read irl bulletpoint as much as possible and achieve a lot of white space. This wouldn't be approrpriate for the more conversational tone of many posts but, even where a densely argued and complex point is being made, you still need some space to aid digestion.
More than the space, punctuation is desirable. Apart from my personal dislike of unrelenting lower case, the length of sentences is crucial to ease of understanding. Seven to eleven words is the ideal. Double that and you're losing people. Treble it and only your mother will plough through to the end. Hard to comply with these strictures and I have at least two sentences over thirty words long in this post.
As with so many other things, I will forgive any grammatical or orthographic eccentricity if there are some clever turns of phrase and the content is sufficiently meaty. But I may well be just another generally snobbish pretentious asshole mentalist.
A lot of people find Gunning's Fog Index handy when learning how to improve their writing style. I would be rubbish, were I writing for a living.