There may be certain behaviors that Google / Bing / et al favor today. It does not mean they will continue to favor them tomorrow.
That's the point of the article that I originally linked, as far as I read it. As search engine algorithms continue to get more and more sophisticated, the "tricks" that people apply today to attempt to gain exposure on page one of the search results may not be necessary. Ultimately it will be truly about the content.
The point of "human readable URLs" really isn't about making them human readable at all... it's about putting keywords into the page link. If we have keywords in our header tags (H1, H2, etc) as well as in our page title, and those keywords also appear in an appropriate fashion within the content as well, then keywords in the URL may
help reinforce the idea that this page is, in fact, about those particular keywords. As stated, Wordpress offers a very simple method for turning this on. The category for the blog post becomes part of the URL, and the title of the blog post becomes the URL as well. But a blog post is not a forum post. When I write a blog post, it may take hours or even days of research. I may document my findings with screen shots. I may search the web for relevant links in order to include them. By the time my blog post is published, hopefully it has been outlined, written, proofed, and finally published. Once it gets to that point, it's not likely to change much, and certainly the title won't. I may write several thousand forum posts over the course of a year, and several dozen blog posts. The relative weight / importance of an individual forum post is just not as high as an individual blog post. So to me it makes sense that Wordpress does more for SEO, simply because it's more important for that platform.
A forum post might take two minutes. Less, if I don't search first.
In my opinion, they're different animals. The amount of effort required to ensure unique, valid, and appropriate "keyword stuffed" URLs is not mandated in this case. I've been running a phpBB board for years and when I search for keywords that I expect to match on my site, I find that without fail my site appears on page one of the results.
Finally, I won't dispute that studies exist that can show that this helps as far as search engine optimization, at least today.
But if you've worked on the web long enough, you know that strategies that worked three years ago are in many cases no longer used, and in some cases may even draw a penalty in the weighting. So if we can agree that forums are not blogs (and vice versa) then perhaps we can also agree that different techniques may also be more or less appropriate.