You said it in the middle there: it's us 1024 types who are in the wrong here, and the sooner we give up this particular windmill the better we will all be.
When I'm buying a hard drive, I really don't care that the 1TB drive has 931 "GB" of space. I do care that one "1 TB" drive will have significantly more space than another "1 TB" drive, but I can usually find that particular info on the side of the box or the manufacturer's web site after a bit of digging.
I don't know how you go shopping for a new hard drive, but I look at what data I have today, compare that to what I had a year or so ago to come up with a year-growth factor, then look for hard drives which are at about two year's larger than my current needs. Then, I look at what's there, decide the wife would have a fit if I spent $1000 on a new drive, and compromise down.
EVEN IF that number that I started out with (how much space I'm using today) was in *bibyte values (as typically reported by the OS), the end decision wouldn't change at all, because anything within, say, 25% of the desired size is just lost in the noise.
Still, though, when I look at how much space I am using, I use the byte counts (OS X gives that in parenthesis right next to the "*bibyte" "friendly" count so it's not like this is much more work to come up with; seems like Windows offers a quick route to the actual byte counts too, right?).
All in all, it seems a moot point. So, in the end, I agree with Alan Green's friends.