*unless you both really hate your names, or hate your family, I can't see why you would do this.
My name means something to me because it's where i come from, knowing my great great great grandmother had the same name makes me feel very attached to it.
I wouldn't just want some random name that had no special meaning or personal history attached.*
Finally someone is saying what I am thinking.
My DH has no relationship with his Dad but likes his name and the history of his ancestors that it represents. I am Mrs DH and the kids have his surname too. My maiden name is my son's middle name.
I am a big fan of family trees and family history and this has meaning and roots. I've traced back one side to the 1700s.
If my sons grew and made up a completely different name for his family my DH and I would be so hurt, like a rejection of their "tribe".
I'm not saying anyone is wrong to create a new surname, but for others, like me, tradition outweighs the desire to do this. It's personal taste rather than a questions of ethics.