Perhaps if trading between different eras was a bit easier, activity would be more robust.
For example, my wife (bless her heart for this) and I are currently building two sets from the '50s. I'm fairly certain that offering the card pictured below for trade in the "T" card section, to help fill in a few holes in our '55 Topps set, would lead to a few responses. The same card, in a centralized, common trading area, would probably lead to quite a few more.
As the title suggests, this is just a thought.
Have a great night, everyone.
Best Regards,
Eric