Sherri Cooper and Jennifer Levin's interview with Collider.com, where they explain why they wanted Kristin as Beauty:
"Question: Since you’re introducing this series to a whole new generation and the CW has a very specific demographic, did you have any type of focus group or young people that you asked their opinion on who should be cast in this role?
Sherri Cooper: We did. We always wanted Kristin Kreuk. My sister-in-law is actually the casting director, and when we started writing it, she immediately said “Oh my God, I know who Catherine (character Catherine Chandler) is,” and we watched footage of her from the beginning. It was always Kristin Kreuk. When we were writing, we didn’t really picture somebody specific when we were developing it, did we?
Jennifer Levin: No, but we did use our assistant who’s a decade younger than us and is now a writer on the show. She was incredibly helpful and is a huge Comic-Con CW fan. So yes, we did."