OK there are two parts to this that I'd need to address in order to be comprehensive!
1. Just personally, I have only asked one guy out in my life. It was in 5th grade. As I recall we didn't go any further than holding hands and kissing on the cheek and passing cutesy little bus-stop notes. (as an aside-I haven't done any more asking because of one reason-solely because of my fear of rejection-and NOT because I have guys like, banging down my door or any nonsense like that lol)
2. Now this is just my opinion, take it or leave it, all opinions on the subjective are right to each invidividual and I respect them as such. I personally don't believe that there are any "shoulds" or "shouldn'ts" to who asks out whom. I think that many men prefer to do the asking, and might be put off by women who ask them out, possibly seeing it as an overly aggressive move, and be thrown off by the typical gender role stereotypical behavior that we usually abide by....it's outside of many men's comfort zones. Just musing here. I think further that women who are ballsy enough to go after what they want-and I do give them props for it-might inadvertently be taking some of the old "thrill of the chase" conundrum. Not always, but sometimes. Alright I've thrown in my two cents, hope I've been somehow useful with my answers =) cheers!