We already have GC turn-ins I don't see the problem or the it won't survive without the demimaterias and allagan coins. The point of this is to rebuild a zone which unlocks a secret shop and more. I'd say that it's better than the GC turns-in if you ask me.

Wanna make them give us a special tokens to use in the shops? Fine it could, point is that they wanted to incentive this with a monetary reward and imho 20k is nothing when a single platinum allagan coin gives you 18k. Imho the only reason they made the weekly cap was to avoid ppl spamming the coins to finish it in 30 mins or so