The obvious reason not to encode assumptions about the statistical distribution of internet traffic in your router hardware is that if the assumptions ever fail (say, because some new P2P service takes off, or video viewing becomes less centralized) your routers will fall over. He's essentially proposing to build centralization and the end of the peer-to-peer internet into routers at the hardware level. Not only that, but anyone who can generate traffic that breaks that assumption can launch a denial-of-service attack against your routers.