They did the ankle ball blue becuase when it was attempted gold it stood out just as much. They thought it would look better where it appears dark and not gold.
As for the hip joints...you xeno said they show on the sitting pose but I didn't notice them. As for the knees...this is a figure that they anticipated would be moved between standing and sitting and full knee range both often and for long periods of time. So they wanted a very sturdy joint. Becuase of where it is in relation to the stand they didn't think covering it would be smart. And having a rubber body was a no go. There's not really a great way to do it unless they went hulk and did a swap out lower torso. Which was looked at but that adds 75-150 to the price and with the throne also makes the box way to big. There isn't a perfect way to do it.
How do you know they looked at these? I don't care about the argument as I agree with your points, if anyone seriously compares this to a $20 toysrus figure then their either an idiot or trolling.
Just curious how you know they tried gold joints and looked at doing a swap out lower torso?