Well, we agree - As per the thread title, the rewards are disappointing.
I think this could be easily solved by coding in Prize Pools (as per my previous post) to adequately reward ranked winners, even keeping some RNG about it, but cutting out any chance to receive greys as a reward for those attempting to win.
Right now there's no incentive to try, and therefore no incentive to pay for a membership (yes yes, I know Chthugha, the Kobans are the reward to you, but I can aim for items by simply not participating at all and get the same payout).
To capture more of my interest in grinding for a contest, a decent reward has to be there and, in my opinion, a handful of Kobans is not enough when the item prizes are the same chance at all levels.