Tablets took off because the screen size is so much better for consuming content and getting certain types of work done. The usefulness of tablets seemed obvio

Tablets took off because the screen size is so much better for consuming content and getting certain types of work done. The usefulness of tablets seemed obvious to me and many others before they became popular. I don't see an obvious use-case for smart-watches, unless they are extremely affordable. $300 is more than twice what I would pay for a fully-featured watch, and that's if there is a killer feature that justifies their existence.