For any serious device there's always importance on the UI that's been there ever since Apple II's came out. Seriously UI is how your users interact with your device if you don't place the highest priority on that how do you expect anyone to use your device for more than a second. UI is the most important aspect of any application/device. Eye candy is (obviously, IMO) bloatware from featuritis and can be done without but helps non-technical people feel a personal connection with the device. Also, eye candy is excellent for marketing purposes and demos since they create a compelling argument for using your device. Yet, eye candy doesn't create a compelling UI it just helps make your UI more interesting and easier to look at.