Oh, and of course, chopping down a few trees.
Before-and-after photos at DumboNYC, like those above, make it clear that several trees have been lost to the renovations. It's possible that before the park re-opens, new trees could be planted; that might appease some urban planners, but it won't satisfy the faeries.
Of course, that's New York's (new?) operating philosophy: if something's in your way, kill it.