To be honest, I was gonna say to remove unbinding. But then, i remembered unbinding requires energy. And we have to work for energy. Thats a challenge. And who doesn't like a good challenge? :)

Lets face it, people have a ton of 4* rarity items that they could sell and have a good amount of crowns right now. It would be worth it, because they would be helping other people and be helping themselves. If you had some 4* evo catlysts but your battle sprite is 5*, you'd want to sell em. But you cant. You cant even sell em to a vendor.. So you would thing you could unbind them. Alas, you can't. Which means it's stuck in your inventory. FOREVER.

If you read the title and the 2nd paragraph, i'm sure you'll think of your inventory and say:
This makes sense, and I like this suggestion.