Systems have an inherent amount of complexity that cannot be reduced. Also known as "The Law of Conservation of Complexity".
The total complexity of a system is a constant.
Making something more simple for a user will add complexity in other areas (i.e. for the developers).
Tesler famously said "Every application has an inherent amount of irreducible complexity. The only question is: Who will have to deal with it—the user, the application developer, or the platform developer?"
Simple isn't simple
It takes a lot of work to make something 'simple'. By reducing complexity for the user, we are shifting complexity onto the designers, developers, etc.
Some products are inherently complex and it would be counter-intuitive to attempt to simplify them (i.e. air travel requires several steps in order for a user to make a decision which is right for them and removing them might be harmful to the user experience.)