Re: How important is looking the part?
Having read many of the replies on this thread and having had time to reconsider the original post, I have another offering.
Fly fishing is , within the sport fishing world, a discipline. The gear is specific to the technique of fly fishing. For instance, the way in which a fly line and fly are cast often require that the fisherman wade into the river or creek to provide for a proper back cast or in order to reach a distant target. Therefore good chest waders are almost a prerequisite in the sport.
Often times we find ourselves fishing in inclement weather and over time we learn that a good jacket, one made to be waterproof and specific for carrying some fly boxes is needed for comfortable use. Because of this fly fishermen often may sport a quality jacket.
If you follow the inference left by the points I've put forth it is easy to understand why or how many fishermen come to look like poster boys for tackle and gear advertising. In many cases I don't think the appearance of a fellow on the water is so much influenced by what they want to look like but more so by the gradual acquisition of proper gear for use in the sport.
Almost any sport which requires implements and outfitting for the proper safety or effective field use will fit the same profile as that of fly fishing. Myself, I don't have everything but after all these years of trial and error I am pretty well outfitted for this sport. I suspect that many here are in this same camp.