Why the lack of Indiana Jones merchandise?

If you quickly peruse the internet, you will see that even the most "cult classic" of films has more t-shirts, posters, action figures, etc than Indiana Jones.

Truly, it is more difficult to find legit/officially licensed Indiana Jones merch than it is, for example, John Carpenter's "Big Trouble in Little China." Why is this? Why does Lucasfilm/Disney hold so tightly to licensing the Indiana Jones brand?