Being in my early 40s, I think this movie made a lot of sense. Josh is so mired in his ways that he won't take anyone's advice even if they have the expertise and the desire to really help him. Jamie is completely open to any ideas and using anything (and anyone) he can find. He thinks everything is "beautiful" and inspiring. I truly admire the work of Noah Baumbach. He always puts his flawed characters in uncomfortable situations. I always want more.
shareAs you age, you become less open...
I know I certainly have lost a certain degree of openness as I've aged, yes. When I was younger everything in life was new, thus I was more willing to be adventurous in big and small ways, step outside my comfort zone, learn from people, etc. Be open to new ideas or things to do.
But I think some of that loss of openness isn't necessarily a negative all the time -- some of it is a positive in the sense that you've learned enough about who you are to now know what you don't like and don't want as well as what you do want and what you have learned from experience. That's fair enough. There's a time for everything. Jamie was in the time of his life where you are open and still going down roads new to you. Josh had been there done that; it's not all that inappropriate to arrive at a place where you know what your comfort zone really is.