Although I understand that orange is just another colour, the already low 'fee' of becoming a donator and having access to more cosmetic items because of donating allows for more people to donate and in turn help the server run.
I don't think any more colours should be added in without donation as they're ID based as Mike said and colour ID's beyond 128 are essentially rare colours which were only implemented into the game at launch of 0.3x. Keep rare things rare.
-1
Edit: Just realised this was a rejected suggestion.
#FreeBK
