Again, do you have any firm data supporting the assertion that this form of network prefetching is so critical?
I've read many comments where people mention performance in ways suggesting they have issues with UI performance, launch time, extensions, etc. Optimizing cold-cache performance the first time someone visits a site won't help with that at all.
Do a quick text search of this Hacker News thread for people talking about Firefox "feeling" slower than Chrome.
Preload is a big underlying "why" of that experience.