Well in the case of someone like George Clooney, who regularly tops "Most Desirable Bachelor" "Ideal Fantasy Husband" etc.-type lists, I think it's an obvious question for a certain type of "journalist" to ask...part of the usual voyeuristic interest in stars' personal lives. Maybe a better question is, why do so many women frame their fantasies about him in that context? Why not just find him sexy and leave it at that?
I don't really notice it much in academia, where overall I'd say most have zero curiosity why their coworkers make the personal choices they do, but when I worked retail I noticed men who were over, say, about 35, and seemed to be actively dating or in a relationship, often got "So when you gonna settle down?"-type questions from both male and female coworkers who were friends with them. The idea seemed to be that you're not really grown up, not really a man until you've made that sort of commitment. I don't remember women in comparable situations getting that line of questioning much, but I do remember women of the same age range who didn't seem to be dating or involved tending to get the "poor thing, she must be lonely"-type comments from coworkers (usually behind their back) while men who weren't dating or involved didn't usually evoke that response. The idea being, I guess, that what women want most is romantic interest from a man, so if they don't have it they must be lonely.
That's all just anecdotal, maybe the people I've known were atypical somehow, but that's the impression I got.
It seems like it's a little different when people back away from the micro-level and look at broad social trends lifted out of context, though. I don't know if you read any of the comments on that article or not, but the majority of people who found the article disturbing in some way seemed to be applying that "not grown up; not responsible" ("selfish", etc.) line of thinking to women. And very often they mentioned lack of children as a symptom of that--even though the article barely mentioned children, even though 40% of them are born to unmarried women now anyway. I guess worrying about where the future of children's welfare is headed (and the anxiety about shifting relationship patterns that tends to provoke) really only rises to the surface for most people when they're looking at broader trends like that. At least in my experience, children aren't really all that often mentioned in whatever arm-twisting about getting married goes on in more everyday contexts.