Agreed with everything you said except

> keeping in mind users don't care about data size, they care about latency.

Users do care about data size since there are still a lot of people on data limited contracts even in the UK which has a fairly healthy mobile market.

What people don't necessarily realise is the connection between the two, I'd quite like it if the mobile browsers had a running total of the total amount of data transferred in that tab on each new visit/refresh.

I'm a programmer and I still don't know which pages are heavy or not (given fixed bandwidth the time to interaction would be a clue but mobile internet latency is all over the map so you can't tell if it's a big site/page or just the mobile internet shitting the bed).