Sidenote - "Why don't they just" shield the electronics rather than making the electronics itself radiation proof? I ask that knowing that there is a legitimate reason (shielding weight?), but it is something I have sincerely often wondered.
PS: If you added up the entire mass of everything ever put into orbit you would not be able to make a shield to guarantee normal equipment would be able to stand a 5 year mission in space.
Now, if you're wondering how better to phrase your questions of this sort, I'm afraid I don't have any specifics, because I'm not sure if I'm just as guilty of this, or if I've successfully rephrased my questions of this sort. What I do is try to imagine that I've spent years designing, building, and debugging the thing in question, and gone through multiple reviews by outside organizations where every design decision was scrutinized, and had many meetings with coworkers (formal and informal) to discuss the thing in question. And then I ask my question in the affirmative, rather than in the negative, such as:
"Why did you do X, would Y also work?"
"I would have done Y. What is it about X or Y that I am missing?"