Even Toyota's own Tacoma line is much more modest than that monstrosity on the left side of the image. I think their business and marketing people saw the trend in America for increasingly larger pickup trucks and pushed back against it, realizing themselves that it's pointless and ridiculous to have a truck that large.
All of the Tacoma's I've driven were pretty straightforward trucks despite it having 4 seats.
It's estimated that Ford makes an average of $10,000 in profit for each F150 sold. Toyota would be stupid to not make a full sized truck to get some of that cash.