Just the fact that Poloniex is completely silent about this astronomically high number of complaints and bad reviews is a huge red flag, this site might be having liquidity issues, or may be malevolent in intent and might try to outright steal customer funds benefiting from a lack of regulation in the crypto space. I would hope very much to be wrong, and for someone to step forward from their company to fix this huge reputational hit they've been getting over the last couple of months...
Simple. They know they can get away with it because they have the volume. That dwarfs any need to please customers. It's always been this way and it'll continue to be so until more discerning and demanding people get involved. However greed will always beat anything else.
It won't continue in US exchanges if the Uniform Law Commission draft uniform virtual currency act gets approved. Coinbase is strongly objecting to it. All exchanges regulated by it would have to give a bond to the department administering the act, and the department gets to specify the amount. There's a possibility of heavy regulation coming soon to all big US exchanges.
http://www.coindesk.com/uniform-regulation-virtual-currency-businesses-coming-state-near/
Prior to being licensed, an applicant is required to post funds, a letter of credit or surety bond with the department administering the act in the amount that the department specifies based on the nature and risks in the applicant’s virtual currency business model.
Non-compliance with these requirements or engaging in unsafe, deceptive, fraudulent acts or misappropriation of customer property, subjects you to enforcement actions which can result in fines, a revocation or suspension of your license or the issuance of a cease and desist order as well as, where appropriate, the referral of the matter for criminal prosecution.