I agree with the majority. To me, it's a destination wedding if the place is chosen not because it is where the couple or their families or someone else close who is hosting live or have lived, but because they think it would be a beautiful or exciting place. I agree, a ship or resort area or a place you have to go for a week almost always will be, but there are others, too.
The distance some or even most of the guests have to travel has nothing to do with it. As others have noticed, at most weddings, there are some people who have to travel. My future son-in-law's family will travel from Israel to Ohio. Still not a destination wedding; it's the bride's hometown (and still our town, and we are the hosts).
As others have pointed out, there are weddings we wouldn't classify as "destination" that are still a little inconsiderate to guests (on the mountaintop at sunrise). And by the same token, not all destination weddings are inconsiderate or inhospitable; indeed, for some weddings, like where the HC have already been married before in BWWs and feel funny about doing it again, or where there is terrible family dysfunction that make a large wedding a very bad idea, a destination wedding can be the perfect thing.
Having read many strings on this subject, it seems to me that the destination weddings that put people off are those that seem to be making the statement, "We care more about an exotic venue than we do about having you with us." And then when people well-meaningly try to avoid pressuring people to spend a lot of money by saying, in effect, "No big deal if you can't come," that just hurts feelings even more.
So maybe -- not for etiquette classification purposes, but for individual decision-making -- the criteria for a "destination wedding" should include context.