If living and being in Japan has taught me anything, it's that generalising from anecdote is not a good idea.
Case in point, if you visit an outlet mall a few miles outside of central Sendai on a weekend, you'd have a lot of trouble convincing anyone that Japanese people aren't making enough babies. It was very, very difficult to spot single people, or even couples without babies crawling all over them on our one day out there.
In a population of nearly 130 million, if there's any generalisation you want to make about Japanese people, you'll find enough anecdotes to put together into a convincing article.
On the usage of mendokusai, I think the author of the article may have misunderstood in the situation he's describing. I believe that in this situation mendokusai meant "It's tiresome to be constantly propositioned by male colleagues at work" rather than "I would have sex with everyone, but I can't be bothered". IME you use mendokusai whenever you're tired of something, along with describing a task that is tiresome.