Because no one goes to watch Michael Mann movies.
Seriously, I don't get it either.
he was a big name in the 80s-ish, i gotta say i only watched 2 films by him, Last Of The Mohicans and Collateral.
Today that i am old, i appreciate Last a lot more, but when i watched it back when, i thought it was meh. Not enough unrealistic explosions n'stuff.
Collateral, i thought it sucked the first time i saw it, then i felt the need to watch it again, and i liked it more. Again, same reason, not enough booms and pewpews for a film about a hitman hitting mans. Mann's films are, from what i can tell, understated; obviously the general public is going to demand a bit more pzzazz.