Cause nobody around here does it but me..I get looks at every shoot I attend, and if they are not capped and crested , they are naked looking in my quivers..  
White 9 inch cap
3 yellow-chartruese high back shields
Black and yellow crest

I have always crested my arrows because I like the looks of it. I don't think that I can see it in flight, but it sure helps me find my arrows when they have snaked under the grass or something.  
But it does add weight and when considering Dr. Ashbys studies that show that we want most of the weight front of center, I can't help wondering if I wouldn't be better off with just a few nice cresting stripes rather than the whole dip.
I have done most of my crown dipping with fletch lack and it is pretty thick, maybe the water based stains some guys are using would be so light that it wouldn't make a difference.  ???

Plain arras just aint cool!Its like any type of weaponry throught history.The embelishments give em some magic.

Crown dipped or not I have found that tapered or brested shafts will perform better than parallel shafts. Not wanting to start a different discussion, but IMO tapering the shaft is a good idea.