The end result is a simpler model. The process of simplifying your model may not be cheap. It's like how you can get some weird set of complex rules and after

The end result is a simpler model. The process of simplifying your model may not be cheap. It's like how you can get some weird set of complex rules and after a bit of time and practice you can just apply them without thinking much about it. However if you suddenly change those rules - even to make them simpler - you'll have to spend awhile readjusting. It doesn't make the changes bad, but it might explain why people trying to keep up with Rust feel it's changing more significantly than it actually is.