when I miss, I know it wasn't the powder charge, therefore it had to be something else. Now, I try to find that something else. Was it table manners or a missed condition. If table manners were good, then something down field, but that isn't always apparent. If it had been apparent I wouldn't have pulled the trigger. Even so, I now investigate more diligently KNOWING it was out there. I shoot score but do test using groups even on the score target. When the load opens up, I know the tune is bad and not because of an over or under charged case. For me, powder charges are one less variable to sort out given that the charge is correct. I am not saying weighing is more accurate, just better for me. As Wilbur said, it makes me happy!
In a different vein, at most score matches, shooting two guns with at most three relays and many times just two, there isn't time to reload at the range anymore. I have to go pre-loaded so weighing becomes an easier proposition in a climate controlled environment.