May-September romances and relationships were fairly common in American culture at the time period when the comics came out. Usually that resulted in young women just becoming adults (18, 19, 20) and marrying an older man who might be 40 and established and able to provide for a family. There were quite a few of these in my hometown. That changed during the sexual revolution of the seventies. All along women had dated and fallen in love with young men, but often ended up discarding them for someone more mature. However with the sexual revolution, people often discounted the advice of their parents and married for love and based upon sexual compatibility. That practice has continued in Hollywood, far overshadowing reality, with lots of married on screen couples showing a significant age gap. Of course the other was considered improbable even foolish up until the mid-nineties when films like The White Palace came out. Having Michael Douglass play Pym doesn't make much sense as it really limits the story and makes casting more difficult. Once comic books were counter-culture or they were strictly juvenile popular culture. Because the demographic in the beginning was 25-35 year old men for the comic based films, then you'd expect to see wish fulfillment for those folks. Now the same people are attending, plus their older fathers who originally read comics like Antman. A good portion of comic readers are women today. I believe sometimes approaching 25%. Since so many have been made, and are pretty guaranteed of success based upon drawing the same folks each time, then more and more mainstream actors are willing to do a blockbuster and then have more economic freedom to do other things like Wonder Boys or even independent films like Solitary Man. One would hope though that they'd cast someone younger...a lot younger than 69. Otherwise he'll be perpetually show musing and having flashbacks about his younger self fighting crime.