"Keep It Simple Stupid"
It's a design principle which things should be kept so stupidly simple that anybody can understand how to use it.
I think they said it violates it cause most of the changes you made either add a lot of options (an option to change a layout that while cool looking isn't really needed, plus the topic icon) or hide stuff making it harder to find (like moving the Submit button under the menu), both things which add complexity.
wow