Last Names...

A certain incident had me really thinking about the importance of last names. We all have one with the exception of famous stage names like Madonna, Cher, Sharika even Beyonce, but us regular folks we'll keep em for now. My question is are last names all that important?

What brought this on is that me as always, meddling in other people's conversation (when will I ever learn to keep my opinion to myself? Probably never.) decided to give some insight to a question my sister had.

Yesterday my sister asked a couple of her friends if they think it would be a good idea to change my niece's last name from her father's to hers, her maiden name, since she pretty much did most of the "raising up". My niece's dad is by no means considered a "dead beat dad" but because of certain circumstances in his life he could not partake much of my niece's life.  Did I forget to mention, me and sister have different last names -- long story, different day.

While her friends were giving her their insights, I took it upon myself to invite myself into the conversation and offer my opinion. Which was...
"Remember we have different last names and because of that reason alone, I didn't forget what mom did or dad did for me/us. That did not play a factor into whom I love more, appreciate more or who did more for us."
At which point my sister decided to literally skip away and play with the kids and pretty much say that the discussion was over, making it quite obvious that my opinion made her feel uncomfortable or upset versus that of her friend's opinions.

So that had me thinking....am I wrong? Does a last name mean that much?

Granted I've been in several relationships and I have imagined having that desired one's last name, "oh how would it feel, how would it sound if my name were "Maria 'insert any of my ex-boyfriends last name here'". Even now that I am in a serious relationship, I still think about how nice it would feel to have his last name.

I know that last names must be semi important since in our society, there is that stigma of how some men want to have at least one son, so that he may carry on the family name. In the old days it was used as a way to imply where you came from or even what was your occupation.
Ex: Maria of El Salvador or Maria of these United States. or John the Blacksmith aka John Blacksmith

I suppose that since birth my last name has been different than that of my brother and sister I never felt as if I was any...different than them. They are still my siblings even though I have my mother's last name and they have my father's. I had the opportunity to take my father's name but ultimately decided that not only did I loved my last name but I knew that eventually, maybe I would end up changing it if I ever decided to marry. Plus I didn't want to offend my mom by changing it. (Talk about issues to discuss in therapy!) And changing my name of a total of 3 times didn't sound like too much fun.

Again I ask am I wrong? Is a last name that important?