>>1819782>>1821049>21:9Hell yeah, I can finally show that much more emptyness around my girl. But seriously, widescreen formats are made for videos where the character's body is unimportant. Mainstream cinema will use it to show a shitload of people/explosions side by side, or close-ups of faces and medium shots if there are few characters.
In general the format doesn't make much sense for animated porn. In most poses portrait formats are most useful for showing a character, since humans tend to occupy more screen height that width if you show their full bodies.