After hanging out here a while, I realize that this board hates a few very specific name "trends"...aidan names, boys names on girls, "y"s in place of "i"s, McK names, etc...but last names as first names? I don't get it. Didn't Andrew, Michael, James, Jackson, Riley, Thomas, etc. etc. all come from last names? What's the difference between those and Sullivan or Payton? Someone explain the hatred for me. Just curious.
Re: last names as first names
I don't mind this trend at all, of course I am biased. I have a Bennett, it is a family name, but I still like a lot of the last names as first names anyway. I believe that most names were a last name at some point in history ( I could be wrong though)
My last name is a common first name so...

I've learned from going back through my genealogy that it was common for your surname to be a derivative of your father's name.. Exp. FitzJohn mean's Son of John. Even after this practice became outdated, several of the names remained as surnames.
I like last names as first names in theory, but in practice it can get annoying if you also have a last name that can be a first name. Interestingly both DH & I have first names which are common last names AND last names which are common first names. Before I was married I was constantly called by my last name by people who saw my name in writing before I personally met them -- like new teachers or coaches. It was especially annoying when I got out into the workforce & casual business associates would mess it up. People I dealt with only over email were the worst offenders.
I couldn't wait to change my name when I got married because at least DH's last name is a common first name for boys. I haven't had one person in 8 years mess up my name now.
Andrew, Michael, James and Thomas are biblical names. Any similar last names were derived from those first names and not vice-versa.
My issue with last names as first names is that it's the appropriation of a random always WASP-y last name that (generally) has nothing to do with one's family or heritage. It's like trying to be pretentious but missing the point -- for most of the people who originally popularized such names they were family names. It's also such a trend right now that it will sound really dated in a few years -- you'll hear the name Sawyer or Peyton and immediately know when he/she was born, and it will be kind of eye-rolling.
I agree with this.