It takes you from the powerful, inspiring, and awesome person that you are to a mere object of lust. You are already beautiful and deserve better than that. When you show cleavage and your legs with mini costumes, it is those parts of your body that are emphasized (by design). It sends the message that the most valuable thing about you is the body parts you're putting on display.
Modesty is annoying. That's right, I said it.
And not just little brother level of annoying. It's like stand-still traffic, spilled hot coffee, only AM radio, and little brother in the back seat level of annoying.
I really, truly, feel this way. Dressing modestly is not easy. You have to search longer when you're at the mall. You can't always embrace the new fashions without a little (or a lot) of modification.
When a man sees a woman whom he thinks is sexy, he's looking at her with one thing in mind: sex. This might be great if every man walking around had a beautiful vision of sex as “a glorious thing created by God to be an act of selfless love, a gift of oneself created for marriage to be an icon and foretaste of the joys of the marriage of Christ and the Church in Heaven!”