GTA V may be well optimized so that it runs pretty well on low-end rigs when set to medium or low settings, but venturing into the high and ultra ranges requires beastly rigs.
Let's not even get into visual enhancement mods here, alright? However, visuals like that come at a hefty price. Neither time was is praised as much as it was when it launched on PC, where when turned all the way up the game's visuals blew everything out of the water. It was praised once more when it launched on current-gen consoles. GTA V was praised for its visuals back when it first launched on last-gen consoles.