I guess most people using it have no idea it's a picture from Playboy, nor a nude picture, nor a controversial picture. I used it a lot myself when I was working on content based image retrieval simply because all the literature was using it. It never even occurred to me I was being controversial or sexist.

Now that I'm aware of the picture's history, I agree that it was a poor choice back then but I disagree that using it today is somehow an endorsement of sexism. Using it today only means you are using the standard image processing image.