Owners of the base game get to play the new faction in online and skirmish mode without paying extra which is nice. It's not a "pay to win" DLC but adding value to the base game by adding another full campaign to the game, equaling to couple of hours of extra distraction. Thus at the price IMO it's OK to make a DLC. It should be noted now that as of writing the DLC is now also available for non-Galaxy use installation.