Well. I don't always show my hairline, but I guess hairlines are emphasized because its what people see when they look at u, and if ur hairline looks very real, it brings a level of realism to your hair system.. So people want to take advantage of that. there are a lot of popular hair styles that show hairline as well. People don't want to be stuck having to wear combdown styles all the time. for me personally i mix it up. i show a little hairline and sometimes i wear my hair down. Not exposing the hairline tho is cool when u have a system that u don't fully trust it.. Maybe a thicker skin system etc.