Why Sasuke only got 1 eye.

[Nebula]

Kishi likes that emo mutated eye crap.
Just look at obito with one sharingan and one rinnegan.

 

[Your Creepy Stalker]

its probably just a combo of sharingan and rinnegan, so he has rinnegan techs and can still use susanoo and ameterasu like he usualy does.