Switch "most popular" to "your site" and it will probably change user's desire to wait for it.

Yeah, that's true.

Also what I left out in my argument is that while popular already, they still might get increased in traffic if they were lighter.

What's more relevant at Facebook's scale is dollars saved per kilobyte shrinked. Because majority of its users will tolerate almost anything at this point, including apps that crash randomly to measure loyalty.