I've talked to some girls about this (once I found out that a lot go commando) and they all say it's more comfortable. They said they don't do it with skirts or sometimes jeans cause it can hurt. I don't think most girls do it to turn on guys, maybe the easier women do.
I go without panties when my husband asks me too. Like if we are going out. Or just when he requests it. I enjoy wearing a dress with nothing on underneath it. Now jeans or shorts with out panties I am not as crazy about. I prefer 100% cotton panties in my crotch area opposed to denium.
Well, going without underwear in jeans is out of the question. But sometimes when I wear knee length or longer skirts, I do go without. Plus when I dress in traditional Pakistani clothing, its almost always without, unless I am having my period.