Maybe I'll add something fresh to the discussion...
My previous truck that I drove for 18 years, was (is, I still have it) a 1997 3/4 ton Chevy pickup with a factory installed 454 under the hood. Can you believe it was only a $600 option?! It was quite a difference going from that, to this.
I could drive that Chevy all day up to 90mph and never have to push the pedal down more than 2 inches. It got 14.5 mpg on it's best day, 11.5 in the city... with a Borla exhaust I'm still not sick of hearing her go. In fact, I rarely get to "open her up" to where she sounds sweet, in the 2800-3400 rpm range.
However, I just drove my 2014 4Runner 6170 miles from Massachusetts, to Michigan, through Iowa and Nebraska to The Grand Canyon, Moab Utah, Leadville Colorado at 12,000 feet to Kansas and back through Pennsylvania. It was a Hell of a 3 week trip and I learned a lot about the truck.
At first I felt the same as you, she seemed to be struggling a bit...seemed. Once I started using "S" mode to get the revs up, she did just fine, even in the thin air of Leadville. 2nd gear at 50mph and well under the redline.
I had no problem at all passing semis and RV's on 75mph roads. Again, S mode is your friend. I've come close to 100 more than a few times passing on those roads...I had plenty of confidence in her.
I was also loaded up with people and cargo, with a Yakima cargo carrier on top. I still averaged 18.2mph the entire 6000 mile trip. Cruise control worked perfect as well.
Off road in Moab she had plenty of low end grunt too, and the traction controls worked very well...at first I forgot I had them, then when I used them on rocks and sand I was genuinely surprised.
You just have to get used to her...either put your foot in it, or start shifting her yourself. The power's there, you just have to find it.