While every engineer may find Search easy and efficient, that is not the experience of most people under many conditions, including those encountered by the users of the systems Craig has referenced—Contacts, iOS, and Lion. Learning to type into a box is easy. Memorizing the names of perhaps several hundred apps so you know what to type into the box, not so easy. Unless you are an engineer.
Graphic designers, left unchecked and unschooled, are likely to aim for maximum visual simplicity at the expense of both learnability and usability. Such interfaces require users to discover new capabilities by clicking around and seeing what happens. Users don't do that.
So much good stuff in here! The second quote about graphic designers, in particular, sounds like what I spent the first 3+ years when I started working in the digital space arguing against, usually on the losing side.