When did this age gap thing start? One year a hundred boys suddenly decided to marry girls four years younger?
I happen to believe that pickiness and obstinance, along with a limited desire to marry is the bigger problem.
I am an am haaretz when it comes to this topic, and I, myself am not sure of the opinions, but...
I hear your side, and think that pickiness, way of life, etc is a factor. But, who says this 'crisis' is new. It could be even in the alte heim and before this problem existed, except that: 1) with communication more advanced, we are more aware nowadays; 2) it was more accepted that unfortunately there would be girls who did not marry, where as nowadays with our wealth and education it is less accepted
Just an observation, feel free to tear it apart. I will not defend my points, as they may just be pointless!