The reason is because they have the aggressive sidewall and look that makes the truck look more aggressive. Until very recently, all terrains just looked so passive on a show truck. Smooth sidewalls and tread patterns that just look wimpy especially on a big wheel
If you are doing the truck for looks, you don’t want a passive wimpy tire. Same reason you run a sporty tire on a car or lowered truck, because an all season tire just looks so pathetic.
Fastforward to now, hybrids and all that are bridging that gap. And they are even sort of trying to make street ish tires for this sort of application. I wanted to try ridge grapplers myself, but the price was stupid so I’m on mud tires.
I think there’s a HUGE disconnect Where people assume that lifted trucks are for off-roading and the Owners are interested in off-roading. And vice versa, that a dude like you with a crawling rig is a “lifted” truck/jeep guy and likes lifted trucks in general.