I suppose it's reasonably well-understood that Hive-engine tokens are currently centralized tokens, unfortunately, although I believe they are working to change that.
In the meantime, while I can't speak for the Hive-engine team, my guess is that once they understand that your exchange fully supports their tokens, they will unblock your account from receiving transfers.
As far as user-creatable smart-contract tokens go, there's several possible alternatives to Hive-engine tokens being designed, as I suppose you are aware. @disregardfiat is working on one and BlockTrades is also planning to create such a system. Both of these are being designed to be fully decentralized when they are introduced.
@blocktrades we are fully support and respect what you and your team doing, but we are finding ourselves in a reality when there are lots of self funding projects which could be built on the Hive Blockchain in case if Hive would have the decentralized tokens... and todays case is another confirmation why real business will not invest in those.
We are at our team fully believe in the Hive potential, and I'm personally proud of being an active member of the community, but in other case we see a lack of attention to the projects we building, and lack of the communication with the HIVE development team (
The importance to Hive of user-creatable decentralized tokens is well-understood by all Hive devs (core and apps devs both), I think.
From my own team's perspective, this is now one of the highest priorities, now that we've overcome the scaling issues for the platform that would have threatened any future growth.