Second, just some hours ago, I read that the mere execution (not the download!) of jQuery takes about a second on an iPhone 3G. These devices and similarly weak ones are still out there, which is easy to forget if you test only on the latest hardware.
Lastly, keep in mind that bandwidth isn't always ideal. Consider mobile: In rural areas, 3G isn't always available. When I'm on the train, loading the slim HN itself often is not an issue, while many other pages simply time out. In developing countries, bandwidths are often very low, too. 56kbps still is a realistic bandwidth. And downloading 45K on a 56kbps connection takes almost 7s.