Wearables, 4K and 8K TVs, connected homes, and self-driving cars may be the mainstream themes dictated by multimillion-dollar corporations. But sometimes a concept pervades all corners of CES, from plucky startups to multinationals. This year: Put a screen on it. Adding a screen to something that usually exists without one seemed to pop up again and again. It's not always a bad idea, but it's nearly always an unusual one.