Very few designs benefit from being thick, and the opposite is also true – most designs improve by being thinner. So yes, thickness of a watch (and the ratio between case width and thickness, and also lug-to-lug distance) is a relevant selection criteria.

Enthusiasts are over-obsessed with size, in general. Look at how many posts there are nervously asking if a watch fits. “I’d love this watch if only it was 40mm instead of 41mm!” Give me a break.

Size on its own is neither good nor bad, neither too big nor too small. It depends on context. I’m currently wearing a 17mm thick TAG Heuer Carrera, and it’s delightful. A 17mm thick dress watch? Hard pass: It would never fit under a shirt cuff. So many people think that there’s some sort of universal ideal size, but it really depends on the design of the watch, the size of the wearer’s wrist, and the type of fit you want. This Carrera would feel silly to me if it was much smaller.