This is a huge problem although poloniex probably won't care.

They are earning a ton of profits from people trading on their platform and paying that around 0.2% fee per trade conducted. They couldn't care less about small players in the system that contribute next to nothing to their profits.

Also by using their site i'm pretty sure in the ToS they state that they are not liable for any losses and the software is provided "as is".

Anyways, if you don't want to trade on their site because of this, then don't. There are alternatives for that. Like Bittrex.