It's not just any ordinary eye you know. With that, Kakashi insta learned any jutsu, got pre cog etc. If you read what I wrote it was you'd know it was just an example. Take away the core/specialty/basic go to's and the person is crippled. Was going to say, take away Sasuke's sharingan, Naruto's chakra reserves/Kurama, Sakura's chakra control (strength) but I didn't think I had to. I think Particle style was the reason for Ohnoki's flying too which he always used while fighting. You gonna try tell me he'd be perfectly okay without that?
Oh and don't forget Kakashi was using his sharingan as a crutch at least twice as long as the examples I gave. Sharingan = any element via copying. Hope you feel stupid, trying to be a smartass