My guess is that Toyota is the only mfg that has enough margin to produce trucks with multiple cab and bed configs.
Definitely a factor... but US sales for Colorados and Rangers are nearly as much as Tundras, and in the Tundra you have an option of 6.5 and 8' beds with the shorter cab, and 5.5 and 6.5' with the long cab. But different companies parse their profits and offerings a little differently. Until recently they didn't feel it was worth it to offer a midsize in the US at all, so...
The Tacoma is definitely more feature/option rich than the Tundra, and I suspect the engineering is better sorted as well. I thought it was funny when people were commenting that the new Tundra should be trouble free and perfect "since Toyota had so long to get it right". No, not how it works! So long between updates means they don't retain staff for this task, and the redesign effort will still be short term and small budget, with people who are mostly new to the platform.