Am I missing something? GW already has rewards. It has exclusive troops, like Ogryn and Penguin ( Updated “Not in chests” list - Gameplay Chat (PC/Mobile) - Gems of War | Forums) that you can only get from playing GW, and it also gives some other rewards like gems.
Sure, rewards are based on ranking, but saying it has “no rewards” is inaccurate.
I do agree the rewards could be better, though.