Multiple reasons. One, having a bag with useful things in it is nice, I think more men would be open to doing it if it wasn't labeled as a "girl thing." Also you know how we always bitch about not having pockets in our pants while men's clothes always have huge pockets? That's a marketing scheme to get us to buy purses. As far as the makeup thing, sometimes our makeup gets -blam!-ed up while we're out and we like to run to the bathroom to fix it. I don't take my full collection with me, but I always keep powder, liner, lip balm/gloss/stick, mascara, and perfume in my purse. I also keep pens, guitar picks, hair ties and clips, and other useful items in there, as well as my phone, money, license, and cards. It's also a convenient place to keep my hat and gloves in the winter when I'm out but I'm inside and don't want to wear them. Seriously boys you're missing out.