I think adding the year is mostly crap. What exactly information would it give, except perhaps the false impression that this article is "antiquated information", when it pretty much holds true, and describes a perrenial issue?
It gives a cue about how many times I've probably seen the article before. Quite useful, IMO. I read this particular article when it came out in 2006... it's convenient to know we're not discussing a novel finding on the same topic.
