Interesting comparison with the US election analysis — I think that is the real parallel — not a simple miscalculation but a wider misunderstanding or mis-judgement as per the term you used.
I think people still don’t understand that in the phrase smart-watch, the watch is the dominant part. This is why traditional watch makers have found a way to adapt traditional timepieces out whereas smartwatch makers struggle. In fact, I think the entire smartwatch is a botched attempt at disrupting a ‘timeless’ market — no pun intended. Fitness trackers though are a completely different thing though and which is why they are succeeding.
I think Pebble’s failure is a sign to smart watch makers that there is still a lot of fundamental homework to be done and as Balint Horvath notes, traversing the Jobs to be Done sequence. I’m hoping to see a real smart watch — which is a watch first and smart in an actual way i.e. solves real jobs that the customer wants/desires.