The proportion of stuff about whatever game some or all of the Hivemind are particularly keen on at a given time may have increased but I don't think the number of other games they write about has diminished, I think there's just more stuff posted on the site in general. I can't prove this of course (well, I could try, but it'd be a hell of a lot more effort than it's worth) but the success of the site means they can afford to devote more time to it, so they can use the extra time to write about whatever they fancy.
I couldn't give a tuppeny toss about Minecraft, for example, but it doesn't bother me that there were shitloads of articles on it. See also Diablo 3, to be honest. But then I know that there'll be games/mods/whatever that I am interested in that they'll write stuff about too.
Swings and roundabouts, but people really manage to make not clicking into an article and having to spend seconds reading article titles out to be a bit of a drama.
"I just spend less than a tenth of a minute skimming the front page paragraph to see if that article interests me. And it doesn't. It doesn't. Damn you, RPS! DAMN YOU!"