I don't think this is a problem unique to Kotaku. News sites in general, including highly respected ones, put across horrible and distorted views of "science" every time they use phrases like 'researchers say' or 'a study has shown'. As you can see http://www.yomiuri.co.jp/adv/wol/dy/opinion/society_081201.htm (at the bottom of the page), this guy is a political scientist, not a doctor or psychologist. That means regardless of whether or not he actually said what Kotaku claims (maybe it was mistranslated, maybe not) he nevertheless has no authority to declare what is and is not a mental illness.
One of my favourite newspaper columns is BadScience by Ben Goldacre in which he regularly comes up with examples of media organisations, companies, governments etc misusing statistics, misrepresenting research etc
Unfortunately it makes it hard for the layman to know how seriously to take things. I can usually see through misuse of statistics and I know some of the phrases to look out for that mean its likely you're reading an article of dubious value but when it comes to (for example) the merits of GM crops I don't have the scientific knowledge to make a considered judgement myself
edit: and on the subject of wanting to be single being a sign of mental illness, nonsense
dozens of possible reasons for it, many of them perfectly logical