Definitely sounds like an alignment issue...brake calipers would not cause something like this unless things were really out of wack, and you'd notice that in other ways. Either the forks are not parallel...forks are not mounted in the triple tree correctly, etc. One other possibility could be unequal amounts of fork oil in each side, causing one side to sag more when you are riding or loaded down. If someone is riding behind you, this might be noticeable to them, your bike running down the road like a dog trots...
There is definitely an alignment problem. Cupping is generally caused by out of balance, poor suspension, or under inflation, or a combo of the three.
Generally, at least on the touring models, we can go through two rear tires to one front, so getting 15-20K out of a front is not unusual. I've got 5K on my Vrod, and the front is showing very little wear compared to the rear, as it should be.