And about 1/5th of the "I've strapped a toy can of dog food on my wrist" from the 360's thickness...
Here's a Rolex[0] (Sea-Dweller 4000). Here's a Moto 360[1].
And now instead of holding eWatches to the same standard as mechanicals, it has turned into another thickness race.
Here's Piaget Altiplano for example: http://blog.luxurybazaar.com/wp-content/uploads/2014/02/Piag...
or
Blancpain Billeret https://s-media-cache-ak0.pinimg.com/236x/62/39/fa/6239fae47...
Mechanical watches under 7mm are already considered thin; more usually they are 9-11mm. Quartz are easily thinner.
I think smartwatches currently around look thicker because of case and lugs design. For example, the Sea-Dweller is 18mm, but the side of the case is not flat all the way like the 360, the case back is actually inset, so it’s less noticeable.