I strong suspect it's a non-techy thing. The only reason it might seem to some here to be a gender thing is because the majority of people here are straight men, and ones girlfield/wife/partner is the person you'll see doing mudane things like typing on a PC.
I can say that one person is male and another person is female without insulting either of them. Pointing out a difference between genders is not automatically derogatory.
No, but saying "hey, your girlfriend does this, my girlfriend does this, too! It's probably because they are both women!" is insulting if there is no reason whatsoever to believe that there really is something genetic behind the behaviour. I have seen the reverse of this too, when a friend visited and told me that I had a big LCD, just like her boyfriend, and that it was typical for males to buy large screens for their computers.
To provide a anecdotal counter point to balance this discussion, I obsessively close windows I'm not using.
I dislike clutter and distraction. If I leave a Twitter client open or IRC I easily get distracted by it, so I'm constantly hitting CMD-W and use Quicksilver to open them when I need distraction. Same with iTunes when no music is playing.
More likely it's a non-tech-person thing. Leaving everything open and clicking around in expose until you find stuff is easy: closing programs and then trying to find where you saved stuff via a file manager is hard.
That's because "tech people" have been conditioned, through the years, by the limitations of the hardware (limited memory) and operating system. It's the OS's job to manage resources, but we still do it anyway. Which is why Apple's upcoming Lion OS with auto-save, auto-resume, window management etc will be a god-send for many people I know.
I like Windows 7's window management features well enough that I leave everything open (most things minimized) all the time. I've got 18 windows in 12 applications open, 3 of them visible. Win7 isn't perfect for this, but it's really pretty pleasant.
I'm also using about 6 gigs of RAM, but since I have 8 to play with, why not? :)