To put it a different way, in the last 10-15 years, auto transmissions have come around to being abit as efficient as a manual and with good shifting algorithms.
If I bought a new truck today, I would choose an auto for a few reasons, none of which being that I don't have to shift it myself. (Unless it was a daily driver in traffic, then shifting s ucks)
1. More /better gear ratios for empty driving. G56 is only a single overdrive.
2. The only manual offered has a horrible clutch so there's another $1500 plus my labor within a year or 2.
3. Resale. Tide has turned. Older manuals ar worth more than crappy old auto trans. New Ones aren't because the autos are better.
4. Power. Autos are tuned for more power without needing to tune the truck. Stick is de tuned. = more $ and loss of warranty to get factory power.
If offered a great deal on a new stick shift Mega cab I'd take it though.