An answer to What was C-3PO talking about when he said, “That’s funny, the damage doesn’t look as bad from out here.” reminded me that my friends and I were discussing this, and we now have a new headcanon.
Premise:
- Droids in the Starwars Universe are the most foul mouthed sentients in the galaxy.
Consequences:
In order to curb their offensive modes of speech (maybe something to do with their own belief in their inherent superiority combined with their suppressed natural urges) manufacturers had to bleep out so many of their words, that they eventually decided to just restrict them from making any sounds other than bleeps, hence 'binary' was created.
Only protocol droids have enough self control to be able to have the 'bleep only' restraints lifted.
Few people bother to learn Binary, as most people would be too disturbed by the innovative and creative use of expletives that most droids employ.
Evidence in canon:
C-3PO: I would much rather have gone with Master Luke than stay here with you. I don't know what all this trouble is about, but I'm sure it must be your fault.
[R2 beeps an angry response]
C-3PO: You watch your language!
It must have been particularly bad for C-3PO to actually comment on it. *8')
Even a protocol droid under pressure doesn't always have the self restraint to avoid being insulting when talking to another droid:
C-3PO: Just open the door, you stupid lug!
C-3PO: Stupid little short-circuit! He'll be quite all right.
C-3PO: Don't call me a mindless philosopher, you overweight glob of grease.
C-3PO: They're not going the wrong way, WE are, you nitwit!
Note, all of the sensible answers presented so far, fail either the realism or the evidence test, so here I offer an option that isn't realistic either, but at least has support in canon and is fun.
