A word from a non-Catholic:
My own Methodist background had clergy wearing clerical wear from the beginning; along with the clerical collar (Anglican), ordained Methodist ministers in England also wore Òpreaching tabsÓ with their black academic gowns (on college campuses) or cassocks (in parishes). Preaching tabs are those two white strips of starched linen which one can see in paintings of John Wesley, hanging down from his clerical collar over his vestments.
I might wear tabs and a cassock/surplice on a feast day such as Epiphany, Christmas, etc., but it’s usually the exception rather than the norm.
Some Methodist clergy (and other Protestants) wear the Roman “tab” collar, for one very simple reason: it’s comfortable. When I wear a collar, however, it’s an Anglican one - several of my seminary classmates were Catholic, and I guess out of respect for them I stick to an Anglican collar (which really is a poor term; as someone noted, collar types are indicative of American/European differences, not faith differences). Nowadays, instead of being made of starched linen, they’re made of acetate/plastic, and pretty comfortable. However, (good) clerical shirts aren’t cheap. I tend to wear black instead of other colors. Some United Methodist bishops wear purple.
Why do Protestant pastors wear them? Much for the same reason as Catholic/E.O.'s - it’s clerical garb denoting function. In some hospitals, chaplains wear them (regardless of faith) to be readily identified. It solves a lot of problems, and also de-emphasizes dress, styles, etc., and emphasizes role, function, and witness. In an increasingly secular nation (I’m in the U.S.), Christ and His representatives need to be seen in the world more than ever.
If you look at the history of clerical garb/street wear (I don’t mean vestments for worship), it has changed a lot in 2000 years, and has had a “fashion trend” of its own.
O+