“Everything should be made as simple as possible, but not simpler.” remains a favorite quote. Oversimplification can cause ruin. What matters is that it is a match to the users, task, and context. There are methods designers can use to induce extra sense of simplicity (progressive disclosure, fish-eye lens logic, etc), but these poses a risk. Consider the airplane cockpit where hiding controls and information just for a cleaner appearance sake could be a very bad idea. Many professional business contexts are like that. Minimal means the smallest necessary set of elements; It does not mean nothing.