Watches in today's cockpits really aren't a tool the way they were in the past. We aren't using our wristwatch as a chronograph to manage dead reckoning the way that was required before such modern luxuries as Loran gasp.
Wristwatches are more about expressing your style. It is more about jewelry. With the exception of a 24 hour Zulu hand, and a 24 hour bezel to be able to quickly reference three timezones, they mainly just look nice.
I have met some pilots that actually use the E6B on their watch, but most just like how it looks.
Aviation does have a very identifiable look, which is mainly what pilots are attracted to. Everyone likes to purchase things that are related to their passion, and flying is no different. Flight watches often resemble instrumentation and bring that part of the pilot's life to their wrist wherever they go.
edit In fact, the first wristwatch was invented just for pilots. One of the first wristwatches ever made was named "Santos" by Louis Cartier, which was made for a famous pilot at that time who complained about having to check his pocket watch while flying. (Source: http://theaviationist.com/2013/12/25/aviation-wrist-watches/)
So, the two things are incredibly closely identified with one another.