In-universe, R2 units are made by Industrial Automaton and 3PO droids by Cybot Galactica, who are bitter rivals. So unless IA puts out a translator droid we haven't seen... The old WEG roleplaying game did have a plugin you could buy to allow R2s to speak Basic, however. If you go with the KOTOR stuff though, the idea that astromechs only speak Binary has been going for nearly 4000 years prior to R2-D2 so you'd have thought the consumers might have twigged it by then. Although they're also depressingly slow about knowing the Sith will always be back. And that superweapons are always more trouble than they are worth.
I always felt it was because Artoo was such an ornery cuss, and speaking of cussing, he could apparently cuss up a blue streak. We do have an apparent example of this whe Threepio tells Artoo to watch his language. Maybe a lot of what Artoo said couldn't be said in English because it would upset the Censors, and up the Rating of the movie...
Both were fighter jock droids in the Clones Wars. R2 was somewhat lucky to have a Jedi as his organic, while Chopper likely had a Clone as his.
To require the purchase of a translator droid package as part of a set, of course. R2D2 and C3P0 tend to be at each others' sides most of the time, so it makes sense.
Mostly that was so the a player character wouldn't be stuck not being able to talk to the party if they didn't have a protocol droid or people with enough skill in droidspeak to understand. On the other hand you could instead get a Chopper that can almost be understood without a translator, and clearly the Ghost crew generally understood Chopper.
Star Wars came into being in the days of 64k computers the size of bread boxes that can make a winking smiley face on the screen after 30 minutes of typing in BASIC, not 64GB computers the size of pocket calculators that can do your homework for you if you know the right questions to ask Siri. So, the notion that even simple bots could speak perfect English was still beyond imagination.
Think how much of the films run time and dialogue would be shaved off if R2 spoke English and Chewie had subtitles so others didn't have to repeat what they'd said!
Maybe. I never used it for that. My friends and I would use headphones, say the word we thought we heard and another would type it in.
Yes, that is the only comic that has R2 vocalizing intelligible speech in English/Basic. All of the other Star Wars comics use onomatopoeia to represent astromech droids' electronic noises; beeps, chirps, warbles, squeals, etc. So the reader has no idea what the droid is "saying" unless another character explains it. Kor