twh, you've hit the nail on the head: it all comes down to the likely use - and that, alas, is more of a design issue than a code issue.
I think back to the home where I grew up. In that home, the outdoor receptacles (remember the ones at the base of the post light at the end of the drive?) were only rarely used, perhaps for the hedge trimmer, or some holiday lights. Maybe a trouble light as you worked on the car.
Now, fast-forward to the house I wired a few years ago. The patio receptacle has been used as the supply to a pond / waterfall, as well as an 'BBQ center" complete with refrigerator. Holiday lighting has expanded to more lights than a 60's airport needed. Nearly everyone uses an outdoor receptacle as the source of power when they build a shed - and only heaven knows what's inside those sheds. Suddenly, the idea of a dedicated circuit for the outdoor receptacles isn't so silly after all.
