Ok, sure I am going to be blasted here, however:
I am in the UK, where the pageant scene isn't nearly as bad as it is in the USA. My daughters WANT to compete and ooze confidence and stage presence. They both already perform in dance festivals and talent shows and love the whole dressing up, being beautified thing. My eldest is 10, my youngest 4 next month.
I would never "expect" them to win, or put pressure on them if they didn't do well. I am not into "sexualising" them or turning them into mini adults I just think they would enjoy the experience and it would be good for them.