GITAARDOCPHIL
A US wife taking the husbands last name is by no means a law, just customary for the culture. I know of a few women that have not used this custom and retained their maiden name. As far as cost, I don't recall how much it cost when I got married 17 yrs ago, not outrageous though. My wife had her name legally changed and took my last name. Similar to your example of Hillary Rodham Clinton, my wife retained her maiden name and added my last name to create a first, middle, and last name. So her legal name change just added another name. I hope my daughter continues this custom. We only gave her a first and last name, not a middle so when she gets married, her last name will become her middle and her husbands last name will become her last name.
As for the celebrities, I am with the understanding that the name changes were done mainly for promotional types of reasons, i.e., "selling" the celebrity name, something that rolls of the tounge, memorable. I'm not sure if I am expressing this correctly, hopefully my point is understandable. It's like advertizing a new car or something, in my opinion.
Also you wondered why names don't get changed back after a divorce. It's a little more complicated--the longer the marriage was. Changing the name requires new driver's lic, social security card, identification, and then all of the other accounts one may have aquired over the years, etc, etc. Now I realize that some people get married older, have shorter marriages, I'm just saying that sometimes it's just not worth the hassle, but there are plenty who have changed their name back.
I hope I have been helpful. BTW, new to the forum, as you can see. Great place.
Rich