they print money and enough users are happy enough. that's no incentive to really get things in order.
kraken is another one. almost every day you see someone complaining about the trade engine failing them somehow.
at this stage of the game i was expecting the whole infrastructure to be much slicker than it is now.
Regulators have, so far, taken a very lax approach. Bitfinex was charged a small fine ($75k IIRC) for mismanaging their margin assets with regard to US customers. I wonder if things will change after the BTC-e seizure.
To be honest, I would have thought that regulated exchanges would face more backlash for the constant API and trade engine failures. Coinbase comes to mind in particular.
Considering Poloniex is based in the US, I have to wonder if they might face some action from regulators/law enforcement given the constant stream of complaints not just about the trading engine or margin lending, but about unwillingness to pay out funds on deposit....