IT seems lazy to me, like they hope that even if the game play is crap they will still make sales purely on the theme on theback of the movie etc...
I don't think they HAVE to not use a commercial theme but they need to worry more about gameplay than integrating some theme.. JMHO..
That said I like my Indy pin a lot, not for the theme which is slightly sentimental for me, but mainly just the gameplay..