I guess we have the internet in combination with his already awesome status to blame for that:
If my assumptions are correct, then the next line of movies will be about Washington or Roosevelt:
I guess we're also fed up with fighting the Nazi's for more than 5 times longer than the actual war took. Or fed up with terrorists. Rather fight some kind of group that won't object into getting killed, like aliens, zombies, supernatural creatures, etc.
I wonder if there will ever be a Fantastic Bunch Of Presidents versus the Alien Zombie Unicorn Clan movie. Perhaps i just gave Tim Burton, Michael Bay and/or Joss Whedon a great idea!