I'd rather have flat colors for background elements and bevels for "active" UI elements like buttons and checkboxes. NEXTSTEP-derived UIs (like Windows 9x) were razor sharp and easy to read... and it's funny how futuristic cyberpunk UIs, like the non-VR interfaces featured in Johnny Mnemonic, were envisaged as being more of the same -- maybe a drop shadow or marble texture on the beveled button -- instead of the indistinct flat-shaded hellscape of today.