They smell terrible. And then they scatter their little stinkbombs everywhere, so that you step on them or bicycle through them, and carry their stench with you for some yards.
I realize they only do this for a brief period in the autumn. It is not brief enough.
Ginkgoes aren't even attractive trees. If magnolias smelled as bad, they would still not be pretty enough to counterbalance the reek. Sure, ginkgoes have that nice fan shape we associate with Japanese art, but they don't flower nicely, and they don't even turn a particularly striking color in the autumn. They may have faced down the dinosaurs, but that was a long time ago, and what have they done for me lately?
They have to be in botanical gardens, I guess, and it's fine if they occur naturally. But to plant an arcade of ginkgoes? On purpose? What are you smoking?
I propose we inaugurate a smelly/pretty scale for trees.