Account-less instant exchanges are preferable by the founders as well
Listing on HitBTC (and if I remember correctly and Bittrex) is a prerequisite for Shapeshift.
Devs dont actually opt for Changelly for various reasons (minergate connections)
We' ve applied to smaller instant ones, waiting for their reply, in the meantime Shapeshift will be the first to reapproach once we get onto HitBTC