It seemed natural to me to want a name that was similar to my boy name. I wanted to keep the same initials, and I didn't want to have to change my signature too much. Kind of mundane reasons, I know, but it was what it was.
My boy name was Keith Lawrence. So Kathy Lauren was a natural choice. I used that here as my user name when I signed up, and I got used to people calling me that. So when it came time to "lock in my final answer" (i.e. legal name change), that's what I went with.
I did have to decide if Kathy was going to be short for Katherine or Kathleen. I went with Kathleen because it is the Irish version. (I was born in Ireland). It was also my mother-in-law's middle name, and I am not above trying for brownie points.

"Kathy" is also age appropriate for my generation. "Lauren" less so, but Lauren Bacall was a well-known movie star at the time I was born, so it is perfectly plausible as a name my parents might have given me.