The standard for adoptability isn't the average person at their peak hours of attention and focus. It's the drunk teenager at 2 in the morning fumbling around in the dark.
A functional WoT should be no more difficult to use than managing your Facebook friends or contacts on your phone. Neither of those are difficult tasks, and are achieved by normal users every day.
What is a “functional WoT”? The main trouble here: it's a really hard conceptually, if you delegate that hardness to 3rd party you will completely lose WoT essence.
You might want to reconsider your analogy. When I was a drunk teenager at 2 in the morning fumbling around in the dark, my attention and focus was at 110%!