For 1 - 2 MPG difference, it's dumb to get a 4.6 vs a 5.7. What little money you might save at the pump, you'll lose in resale value. And I don't remember ever thinking to myself when towing/hauling anything, Geeze, I wish I had less horsepower.
I agree with you. I've been driving a 2007 Tundra 5.7L since 2010. I follow a lot of Tundra sites and the general consensus on them is that the 4.6 is just as reliable as the 5.7, but has a bit less power. Most say that the power difference isn't a big deal until it comes to towing bigger loads, however there's not much of an upside in MPG. Like you mentioned, 1-2 MPG and again as you stated, the resale value is a bit lower.