Of course you are completely right! But Sutton at 50 seems about the same age as Roz at 46 or Donna at 41. She's got a girlish air about her that doesn't make the story lose its sense.
Are there any other expert comediennes in their 30's? At least ones who could generate publicity and carry a big production. (I know that given it's Encores, that is not so essential, but I don't know if Mattress would have had the success it's had with an unknown Winnifred.)