Nice summary by Michael Robson of 21tiger on how simplicity makes your apps better. This is from his review of Tapworthy: Designing Great iPhone Apps (affiliate link) by Josh Clark:
Yes, I know, there are a few of you out there rolling your eyes at this. I’ve obviously drank the Apple Kool-aid and I’m going to start rattling off all the ways software, technology, and apps should be oversimplified like the Japanese Dojo, with clean white interfaces and Helvetica Neue text. It’s not that there’s something great about white, but there is something incredibly fantastic about unitasking. I’m sorry if all this Zen stuff is putting a cramp in your zafu, but you have to understand just how much of a pain in the ass (for designers and users) complexity really is. Complexity is wasteful. Simplicity is about maximizing utility.