Payload to payload is the only thing that matters. You don't get cool points for building a heavier truck.
I wasn't bringing up "cool points," though I know that a select few here like to argue about those like there is no tomorrow.
When you build a heavier truck (to include more fuel capacity, among other factors), you see a bigger hit to GVWR.
The extremely short bed of the Crew Cab almost makes the payload discussion a moot point anyhow. Double Cab Tundra's still have decent enough payload for what the 1/2 ton trucks are designed to do. The current Tundra's specs are more than adequate given how
most 1/2 ton owners use (or rather don't use) their trucks. The next gen Tundra will likely see an improvement in those payload specs.
A lot of people pick the Tundra apart based on #'s and specs; recent sales trends would indicate that most Tundra buyers really aren't too concerned about those issues.
Everyone has their mind made up and no amount of discussion is going to change that.