I'll preface this with the fact that I love the item exchange tickets. They're a generous and fun addition to the game, and will further entice free-to-play, lower-spending , and otherwise thrifty/economical players to stay around. I hope it will strike a good balance between increasing player resources and getting people to stick around and spend to keep the game going.
I do have one suggestion: at the moment it seems that you can only use the item to exchange for a piece of gear if you are looking at a Hero's current gearset and the item has not been equipped. That means you can't look ahead at future rarities and use the tickets in advance, or for heroes that you haven't built up yet. It somewhat limits the usefulness of the item and makes purchasing gear in advance for organizational or contest point-getting purposes impossible.
Is there a way to add the Exchange button to all contexts of item crafting, including when traversing a crafting tree?