So no one can do a MITM attack and change the SHA1 checksum, OpenPGP Key ID, file lengths and code signing certificate fingerprints as you download package-integrity.html?
Now, the fact that people are more inclined to trust the bundled ca keys, rather than a web-of-trust backed pgp key is generally just because people don't understand trust.
Say, if you're in Thailand[1] and require a secure way to communicate, where do you get your os/browser-bundled ca keys? Do you trust a CA that is under influence of the Thai government? Under influence of a sympathetic government?
Do you really trust all the CA keys bundled with your os/browser/phone? Do you know which they are? If not, please don't spread FUD wrt web-of-trust based trust models.
To be clear, both have a bootstrap problem -- but only web-of-trust offers a reasonable way for the individual to ensure proper trust chains. No trust chain is (by definition) without trust, so no model (ca or wot) is immune to being betrayed. But at least wot is designed for the user to be able to influence (and be aware of) trust -- and for easy auditing (most keys are personal, or anchored to personal ids, while it can often be hard to tell who are able to access ca keys and sign possibly rogue certs).
[1] http://www.cbc.ca/news/world/thai-police-we-ll-get-you-for-j...
A distributed system that verifies identity would be much better. For example, namecoin based identities and checksums committed to the blockchain.
In fact, any self-signed public key system with a MAC distributed to many sources would be good enough. It doesn't have to have proof of work. The only requirement is that there are enough root CAs that you can't compromise them all.
This should be taken care of by browsers themselves!
I wrote this 3 years ago and since then nothing has been done: https://news.ycombinator.com/item?id=2024164
I think there is movement on this type of system, but it's slow because people don't realize just how insecure HTTPS is when CAs and the US government are involved.