I just came to suggest this as well.
I've never been on a game before with a 1:15,000 exchange rate for its premium currency, and it's driving me nuts. It's awful.
This has nothing to do with moonstone paste or crafting, it's entirely about the value of currency. Allowing any items or wolves on the Flea Market to be listable for moonstone shards instead would allow us the flexibility to price cheaper items for the premium currency.
It's just like having cents/nickels/dimes/etc in the real world. Imagine you're buying individual pieces of candy, but you only have entire $1 bills. You don't want to pay $1 for a single peppermint! So we have dimes instead. But the $1 bills are moonstones and our change is just in moonstone shards.
Or putting it another way, if I want to sell a boring G3 wolf for premium currency, my options are basically listing it for the equivalent of 15,000 pebbles at the cheapest, and my next cheapest option is 30,000 pebbles. There's just no room for fine-tuning. If you want to undercut someone in moonstones, you HAVE to undercut them by 15,000 pebbles. It's so demotivating to see 15 scarves listed at 2 moonstones and knowing if I want to be cheaper than them, I'm accepting literally half of the value those ones are at.