Their reinforce cost was brought up to prevent Rear Echelon blobs of doom which is the current meta for team games and low tier 1v1's. This tactic would of been made even stronger with the current buffs to rear echelon troops.
While I disagree that this is how it should of been solved this is the way Relic chose. I guess we'll see if they were overnerfed/buffed in time.
