It's not a smartphone with a smaller screen. Interactions are as important as on a tv set. Therefore is a minimum of interaction needed. More important is the information displayed and how it trying to gain the wearer's attention (visual, acoustic and tactile).
Watches are still a status symbol. Instant individualization would fit in, like:
A watch is a highly personal device. It could carry also highly personal information, which only could be accessed in combination with the owner of the data. That information could be:
Activity trackers are partially established but still look more like labeling of the wearer. It's has a single purpose which soon will be obsolete. The iPhone M7 chip is heralding this.
via Web Summit 2013