Hey Chris. Good to hear from you, and great question. I have said it before, your site and the knowledge you provide is unparalleled, and you are the foremost ambassador for football collecting..Thanks!
Likewise, I agree with all the previous posts, but I think this is the single biggest factor...
"..Did more current sports collectors grow up in an era and location where baseball and its heroes were simply more relevant?"...yes.
Football has/had it's heroes, legends and lore..but not to the extent baseball had.
Another big factor is the influence baseball cards had on fueling collecting interests.
If you compare between baseball and football something like collecting equipment, i think you will find manly similarities. For example I have found the baseball glove collecting universe to be similar in size and passion as the football helmet collecting world - But when it comes to other items such as game and team related ephemera, and souvenirs, this is when the influence of baseball heroes kicks in, and baseball cards was the fuel for much of it.
For me personally I have a similar amount of football as baseball items, as well as just about every other sport
