Halo 3 multiplayer maps

This question has been on my mind for quiet a while. Is there any particular reason why Halo 3 DLC still costs about the same in the Marketplace? The game is 5 years old and the last DLC, which came out with Halo 3:ODST, came out 3 years ago. Any reason why it isn’t free at this point?

Microsoft controls the price, I don’t see why they would make it free, they can still make money off it.

The Halo Wars DLC is still full priced and will be for months, the Halo 3 DLC got huge sale reductions, minus the Mythic Map Pack II.