>> Without being able to determine future road conditions then automatics can't guarantee being in the "right" gear for the up coming section of road. Be that due to traffic, grading, weather, banking, sharpness of corner etc.

Latest Rolls-Royce Wraith does exactly that - it uses the GPS map data to change gears in advance as it is approaching a turn in the road. I am sure that this technology will be available in ordinary cars soon enough.