Lack of visual distinction is a general problem with the current design trends. Even Apple suffers from it at times—in Xcode, it's impossible to tell whether certain elements are interactive (buttons vs passive status indicators) without clicking on them.

The thing that drives me up the wall is when text inputs are not made obvious. Google in particular is notorious for not giving any indication that something is a text box, as opposed to just static text. I can't count the number of times I have tried to focus and type into something that I thought was a text field, only to discover that nothing was happening.