Why are Germany repatriating their gold? Why do they want it in their own hands? Why go through all that trouble instead of just selling? Why would they want to keep holding onto a "piss poor investment"?
Regarding China, the article's author believes that China has been accumulating gold. The last known official figure is from 2009 and since then imports continue to rise, which in the authors opinion, have been destined for the Central Bank.
As for Russia, they have been accumulating gold for a few years now, and it's right there in the article. "It owned 400 tonnes of gold at end of 2006... At the end of last year, the central bank held nearly 950 tonnes of gold".
If you want to dismiss gold as a "piss poor investment" that's fine, but not everyone shares your view or your investment objectives.