Problem is RTS tend to push for 1v1 e-sport gigachad tourney gaming while 95% of the playerbase want to play SP and 3v3,4v4, comp stomps.
SC2 was pushing esport try hards, yet it had extremely large casual playerbase.
But it had game modes and creative tools to support that.
SC2 coop commanders was fun af for me, and I'm afraid we'll never see such game mode ever again, tho HW3 will make an attempt.