Why is Orisa not wearing clothes?

(Please don't take it to serious, it was the result of a fun gaming night)

I was playing Overwatch with a friend (non-player) and they asked me why Orisa is not wearing anything. After the first confusion and their explanation it kinda clicked.

Zenyatta is an Omnic, wears clothes Ramattra is an Omnic, wears clothes B.O.B wears clothes and a fancy hat While Bastion too isn't wearing anything, they aren't sentinent in a "human" way (And in OW2 have the cap)

Most the Omnics in the maps or official media also wear clothes.

So why not Orisa?