Believe it or not, jimnysf, Chenoweth was the #1 choice for Elle Woods back when the musical was announced. They started to write the role around her talents up until she actually responded to their request of having her star in the workshop. Her reply was "no". Chenoweth did not believe, and probably still doesn't, that Legally Blonde could work as a musical. She has stated it many times in interviews. It's not that big of a secret. Laura Bell Bundy took the steering wheel ever since.
She could definitely have done the role 7 years ago off the heels of You're a Good Man Charlie Brown. She would have been 32 and the role would not have been too young for her. However, by that point the movie would not have been made and no one would have even thought of musicalizing it. If Chenoweth ever did the role, though, her portrayal would have been a lot more like Reese Witherspoon's. A somewhat quirkier version of Witherspoon's performance. Which, in all honesty, would have been perfectly fine with me.
"Sing the words, Patti!!!!" Stephen Sondheim to Patti LuPone.