If done well, then contrast will replace color for many things (e.g. menu bars) as a separating function. If done poorly, then it will look horrible because th

If done well, then contrast will replace color for many things (e.g. menu bars) as a separating function. If done poorly, then it will look horrible because they got the contrast wrong. High contrast should be used where you want someone to pay attention (like an "exit only" market on a US freeway exit). Low contrast where you want something to fade into the background (like a mile marker). The problem with "flat" designs is that it seems hard to get it done well. Just think how long it took the industry to get the "ok" & "cancel" buttons to highlight in a consistent way for users.