Kevin Kelly, editor of Wired has said:

Fancy algorithms and cool technology make true anonymity in mediated environments more possible today than ever before…however, in every system I have seen where anonymity becomes common, the system fails. Anonymity is like a rare-earth metal…a necessary ingredient in keeping a cell alive, but the amount needed is a mere hard-to-measure trace. In larger doses these heavy metals are some of the most toxic substances. In vanishingly small doses, it’s good for the system by enabling the occasional whistleblower or persecuted fringe. But if anonymity is present in any significant quantity, it will poison the system…Trust requires persistent identity. In the end, the more trust the better. Like all toxins, anonymity should be kept as close to zero as possible.

In short, require login.