What IS it about our 20s?

I just read this article from the Wall Street Journal.  It came up on my twitter feed and it was too serendipitous not to explore.  Kay Hymowitz is lamenting on her book titled, "Manning Up: How the Rise of Women Has Turned Men Into Boys."  This is a topic that has bothered me almost since I started college.  Since turning 20, my boyfriends thereafter were terrified by the thought of growing up and oh no! don't say it!  marriage.  I realize that this is not the case with every 20-something male- I have a handful of friends engaged and married happily to mature guys who want to commit to them- but like Kay says, I think the majority are stuck in lala land when it comes to actually growing up and being a man.  Maybe it's because I'm a female and my role in the evolutionary chain of events of the past has been domestic, but I'm not scared to talk about marriage or just growing up in general.  A couple of weeks ago I found myself among some old friends and an ex from my early years of undergrad.  They were all lamenting on how they wished they were still in college and he actually said that he would give anything to be transported back to freshmen year.  What?  Why?  Freshmen year I was awkwardly trying to find my way around campus, hadn't found my true friends and had no clue what direction I wanted my life to take.  Maybe I'm weird, but I think Kay's article backs me up when I say I like having some responsibility.  I like the fact that I am no longer a 19 year old girl going to frat parties and having no real direction or purpose for my life.  So much of our lives as Americans are defined by our careers, they seem to be our "purpose" now, when throughout history family has filled that role.  I am enjoying where I am in my professional life right now because I have had the opportunities to flesh out where I want to be and where I can see myself and implement the tasks needed to accomplish my goals.  Do guys think like this?  According to Kay they are not.  She says that women are becoming more successful than men because we are goal oriented and guys are falling behind.  Is it fair to blame modern man's lack of ambition on women though?  Why is it so hard to pull your brain out of college mode and realize it isn't the end of the world to be an adult?  Yeah, I loved college and there are many times I wish I was still living in my sorority house having a chef cook me unlimited grilled cheese, but those times have their place, and that is in the past.  Memories are happy reminders of the times that made us who we are NOW.  Now is the key word, why constantly wish to live in the past?  Even if someone is not happy with the current position in his or her life, is regression really the answer?  No.  Why?  Because time travel isn't possible.   I liked this article, but I'm also a little frustrated by the fact that my successfulness could be blamed for keeping "boys" from becoming "men".  I refuse to take responsibility for that.  If you're a guy, or as Kay says, an "aging frat boy", man up!  If you're intimidated by women in the workplace or the fact they may be better at school than you, step up to the challenge and compete right along with us.  Dare us to be equals.   Kay also says that men are more successful at work when married.   If marriage helps one be successful, why are males so scared of it?  Broken down it's really just a type of social order, a different way to file your taxes.  Guys don't have to do it alone with only their bros, they just are choosing to, perhaps out of fear?  Well, I am woman, hear me roar, but I don't really bite...