I like to change my character's appearance to keep it fresh. I changed the armour colour about once an hour during the BWE. I don't know if ANet plan to implement a barber for release, but I really hope so.
Pretty much every MMO I've played makes you pay real money to 're-customise' your character (change face appearance/height etc.) but most of them (excluding Aion and Rift) allow you to change your hair/fur/piercings etc. for a small amount of in-game money. And I just cannot understand why anyone wouldn't do this.
Charging RL money for plastic surgery I understand but we should at least be able to change something as simple as hair/facial hair, or have the people of Tyria not invented scissors and razors yet?
If ANet still want a way to make money off of haircuts and such, they could implement this idea for additional hairstyles:
It would work like this. You walk into the barber shop and sit down and a little Asura hops on to a stool and asks you how you want it cut. Then a menu pops up with all the hairstyles that are available at launch. You can then pick the new hairstyle you want, then choose the color from the various dyes you've aquired on your journey. You can even mix dyes to create unique colors/even highlights. There is also a link you can click that will send you to the cash shop where you can preview any new "Hair Packs" that may be available for purchase. Hair Packs could contain around 5 different hairstyles for both male and females the race you choose. Charr could have different fur patterns.
There could also be tattoo parlors added later on, as others have suggested in this thread. Extra tattoos could be sold later on as well.