As a designer:
It's my *job* to make sure the game runs just fine as written.
It's my *responsibility* to make a system framework that is solid enough that it can stand a hellova lot of twisting and warping without breaking.
It's my *honor* to supply alternate rules in the game that can be slotted in, yanked out, and used with no further work, so folks can configure things the way they like.
It is my *pleasure* to give folks tools that can change the setting safely, without any fear on their part of breaking anything.
As a GM:
It is my *right* to screw around as much as I want with rules, whether or not the designer allows for it.