I know many people may be ok with it, but honestly, I like the fact that people are 'stuck' with the name they choose. I can usually tell a lot about a person by the name they chose, and the trophies they have.
Example: On Home, when you see a 'female' with a name like GangstaThug2010, you already know it's a guy. Or if you see another with SweetHoney449 and has 0% trophies, you know it's a made up account (and still, probably a guy).
Also, the Name is what allows you to avoid people that just like to harass others. When you see BeiberFan773 and he annoys you, or won't leave you alone, you can either avoid or block the person. If they can change their name, you have no way of knowing it's that same annoying person, so you get duped into being around them again. If I don't like being around someone, I don't want them to be able to use the system to be able to come annoy me again. Once is all I should have to deal with them.
Your Name+Trophies = Identity. When you allow people to change the name, it just makes it a lot easier for people who like to deceive, harass, and generally annoy others.