> First up is the 'new tab' chicklet in the Chrome tab bar. Somewhere around Chrome 16 the '+' disappeared from it, leaving a little ghost of a button that, to my mind, wouldn't be recognized for what it was by a user who hadn't already formed their mental model on earlier versions of Chrome.

I'd noticed this and it was very irritating! I assumed it was a bug and for whatever reason the image was missing, not that they had intentionally removed it. That's nonsensical to me, without the + being there it indicates... nothing. His point is exactly right.