Here's the deal:
When you pass out you are obviously unaware of all the things that happen to you. First, you dont know whether your friends will leave you inside the bar or take you home. You dont know what strangers would do to you (because they can take advantage of you, or worse, take embarrassing photos of you and post it on Facebook), and you would not know for how long you'd stay unconscious.
When you vomit, you feel a lot better afterwards. You stay awake, and you embarrass yourself in public. However, when you puke, you can always choose where to do that. Hopefully, its inside the loo.