Also form: bing, baidu, duckduckgo, yahoo. My posts were many times on reddit and in 3 years I've been 4 times on HN with +500 upvotes. Currently 1-3 visitors per day come from search results, 0 or 1 are from google. I use goaccess and piwik.

Any chance this is a tracking issue? You might be losing referer information because of the 301, see [1].

[1]: http://piwik.org/faq/troubleshooting/#faq_51

I disagree. A site can get (a decent amount of) traffic from Google even without giving it (Google) the open access to ALL the activity taking place on the site by way of using the Webmaster Tools.

That's.. not how Google Webmaster works.