Thanks for your feedback. Yes, we are aware of the problem, our withdrawal system was designed when Bitcoin was advertised as a cheap way to transfer money. On the one hand withdrawals are automatic (to minimize risks of holding others' bitcoins) and we don't want to charge users for them. On the other hand we do micro-transactions, so we can't set high fees.

The current fee of ~20 satoshi per byte eats about 1% of the transferred value. We can probably double it, but will it suffice? It looks like the Bitcoin Core team decided to price out all the low value transactions until the Lightning adoption. And it is unclear yet if/when it happens and what is a 'low value' transaction in their understanding. Anything less than $10? $100? or $1000? I don't know.

Anyway, micro-transactions are doomed to be low priority. And since nowadays low priority transactions may take weeks to get confirmed, we are in fact forced to increase the transaction fees (and a the threshold for automatic withdrawals) and/or add an optional withdrawal fee.

We are working on it, sorry for the inconvenience.