With Ockham's Razor, 14th century logician William of Ockham stipulated that "...all else being equal, the simpler of two solutions will be the better choice". A few years later, Renaissance icon Leonardo da Vinci declared that "...simplicity is the ultimate sophistication". 20th century poet warrior observed that "...perfection is attained not when no more can be added, but when no more can be removed." And famous fashion designer Coco Chanel affirmed that "...simplicity is the keynote of all true elegance".
Web design is a mixed discipline--part art, part science. Those parts can work at cross purposes. But in the words of wisdom above, they converge. Nowhere does the K-I-S-S principle apply more so than on "the Net". There are exceptions, but most Web surfers are busy people with short attention spans. A simple message will penetrate faster than one that is complex or complicated. A clean layout will convey that message better than one that is convoluted or cluttered. And the delivery should be effective regardless of device (PC, Mac, iPad or other), agent (Internet Explorer, Firefox, Mobile Safari, etc.) or screen resolution (800x600 ... 1024x768 ... 1920x1200 ...).
For results-oriented web design, "Cool!" is only cool when it is also clear, concise and consistent across all relevant media. Your website's flash intro may be wicked cool on your PC screen, for example, but how does it look on a Flash-free Web 3.0 device like the Apple iPad?
Do you want website content that is clear, concise and cross-platform?