I think it's going to come down to how consumers perceive the iPad. If they see it as a simplified computer, then you're absolutely right. If, however, they start treating it like a household appliance, one that simply cuts many more specialized tools out of the picture, then I think digital photo frames might be among the ones to do. When you can call up your photos in a slideshow at any time on a machine that makes doing so feel intuitive, you might not like the programmable frame.
But, as I said, I could be wrong. My own apathy for the product certainly isn't anybody else's.