Simplicity takes effort. It takes time. And you often cannot write simple software in the first version because you are designing it as you go. Simplicity comes from maturity both in the product design and the development staff, and is a long term goal.
It is not something that you achieve by critiquing individual PRs, but by insightful long-term thought into how to solve your problem with your code, and many refactors over time.
It is wise strive for simplicity in all code you write, but wiser to have the patience to let it develop over the lifecycle of your product.