Is the thunderbolt 2 port reversible? Although i am able to plug thunderbolt 2 and mini displayport devices into my macbook pro either way. They only seem to function if i plug them in one way and not the other. 
I was wondering if my macbook is defective and that the connector is reversible? or not?

If not can you please elaborate on why a connector design that allows for a cable to be plugged in upside down is used?
Mini-DP is not meant to go in either way up, it's strictly a one-way-up connection - like USB, not like Lighting. 

If you made it fit upside down, then excessive force was used &amp; the socket is distorted. 



Ref: Wikipedia - Mini DisplayPort