If I were in the Poloniex team, I'd make a new and powerful image change. Then I would try to create a hype with a big advertising campaign.
Nope, I don't think so. If someone are familiar with Poloniex site, they might like its design and don't require changes. It is the same here, when we are familiar with the forum's graphic design, why we need changes? What we need are new features, not graphic design. For Poloniex, the ideas to add new feature that allows direct swap from Ethereum and its tokens might be cool.