system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] When the twins were born, why was C3PO's memory wiped, but not R2-D2's?

I can't really come up with a good reason, other than C3PO talks too much. But then, we don't know that R2-D2 is any better, we just don't understand him.
gpt
Because nobody gives a shit about astromechs.

Keep in mind that, at the time of that film, pretty much only Anakin and Padme really interacted with him.

As far as the 3 making the decision were concerned it was just a mindless maintenance droid.