Because it reduces predictability at first. It used to be that I could predict what site would be at the top when I typed even a single letter, so I could trip

Because it reduces predictability at first. It used to be that I could predict what site would be at the top when I typed even a single letter, so I could triple-click, hit a letter, down-arrow, enter, and not have to actually parse what the dropdown list says. Safari (on my Mac, anyway) still has this property, except without the down-arrow, so it's even faster. With the "ultra-cool bar" or whatever it's called, I have to pay attention each and every time, which slows my browsing to the eight or ten sites I actually visit most, but which I don't bother to bookmark because I know exactly where they are.