During a recent interview on Watch What Happens Live with Andy Cohen, Christina Applegate opened up, and revealed that she didn't exactly "turn down" the lead role, but just felt that it wasn't the best career move for her at the time of Legally Blonde's casting. The Married with Children star was burnt out from playing Kelly Bundy on the show where her main motivation was to be the stereotypical blonde daughter of Ed O'Neill's character. So when the movie script for the 2001 hit landed in her lap, she felt it was just too close to the character she was trying so desperately to avoid. (via Cheat Sheet)

Instead, ET Canada reported that Applegate wanted to look into starring in independent movies instead of major blockbusters. During her time on WWHL, the actress revealed to her fans that she also did not enjoy attending red carpet events. The actress explained to Cohen, that at that time in her career she was going through a bit of a rebellious phase where she simply didn't want to comply with all the press and promotion that would come from a blockbuster movie. She jokingly made fun of herself, reminiscing that she would say, "I don't do this kind of stuff." 

As chance would have it, Applegate's decisions allowed Witherspoon to land the role of a lifetime.