I think with this game series there is an element of supporting its future by buying the latest release, as it helps to fund future development work, and we know that there are a lot of new features the team want to add to the game. The short term view is quite acceptable "don't buy the game as it is not delivering what i want" or there is the longer term view "buy the game as it secures the future game development work for the next releases" (and will be plenty to enjoy with the new Battle of the Buldge environment, maps, campaigns and units while you are waiting)