It's not really broken. It's just not obvious what's being considered to get a rating as it's going through a bunch of people. Also it depends on when it was released and what world events were going on. Going back and rerating them would be more confusing, what was the rating 10 years ago was valid 10 years ago but wouldn't be today.

They admit that they don't always get it right but it's better than no rating at all. Because people need flat numbers and ratings or else they aren't going to watch a movie period.

Specifically when it comes to the G rating, parents are going to watch a movie based on that alone. Otherwise what they'll do is ask around like "is this ok for my kid?" which lessens the chance of them actually seeing the movie.

I'd argue that people just aren't respecting animation the way they should which makes ratings more important. Then animations have to put itself in a box. It's not inherently the rating, in the end audiences dictate what ratings are for.