It's a fictional universe. There is absolutely nothing that says that you can't do it that way, and it makes sense to enact these changes in the interest of improving the story.

3PO and R2 being there doesn't mean they're getting the spotlight or anything, but they should have a reason to be there. They're not that funny, so they can't serve their intended purpose of comic relief.

On the other hand, if it's symbolic and kind of sad, it fits with the tone of the end of the PT and mirrors the main events of the story.

An interesting way of doing it would be to make 3PO into his original conception, a car salesman kind of guy. He'd have his own small character arc where he learns to not be such a jerk, and then in the interest of protecting secrets, he agrees to have his memory wiped.