What people care about is service, promotions, and kinds of other benefits they can get from exchanges they use. I don't deny that fact that past reputation and current total volume on exchanges are determinant factors that significant affect choices of investors or traders when they have to choose between exchanges. For whales, or experienced investors and traders, they care more about security and reputation of exchanges. In contrast, small traders or investors tend to prefer exchanges that can give them short term benefits through give aways, promotions, ref rewards and so on. Poloniex is a US. based exchange, so it has to obey strict rules in that nation. However generally I don't think Poloniex actually has bad reputation.
I have known poloniex o be a very good exchanges with very good reputation, even after losing their volumes to some of these other great exchanges like Binance, they were still performing well in their little way, while they were performing well then before some exchanges pushed them aside, they were too relax at their position and didnt do what they should have done, no king will remain a king forever.
I am sure now that they have realized that new strategies is what will continue to hold a company to the top, they will surely perform better now in this their new rebirth based on past experiences.