It's been a trend for a while now to make hair in this manor, it's to make posing and other fine adjustments easier to see where otherwise once the hair is loaded half (or all) the face becomes hidden. The only problem I have found is in poseing the feet since it casts a dark shadow, but shadows can be turned off while poseing to overcome that issue too. It does make it a bit difficult when poseing hair or if you want to 'see' the hair's texture when decieding what color to go with...but then I guess one can't have their cake and eat it too, right? Oh, and it has nothing to do with a transparancy applied, it's in the code (sorry can't think of the line at the moment)