Yes, but who gets the better time spots? People are already pissed that time zones are based on England's time, how angry do you think they will be when they get some illogical time zone while the anglo-saxons get to keep the am in the morning and the pm in the actual afternoon?
Why redesign the watches? This problem doesn't exist in the places that use the 24h format (like most of the world around North America). We can use both time formats. I can either say 9 in the evening or 21 and everybody gets it.
Well, when someone asks me what time it is now, I don't say, "The minute hand of my watch is pointing at the 1, and the hour hand slightly past the 3." Instead I translate it to "three-oh-five". Wouldn't be too much of a stretch to say 15:05 instead.
(My point being that many watches and clocks already don't give us the literal time as it's spoken, just a representation.)
Edit: although just to be clear, I don't actually think we should switch to a single time zone. It would cause all kinds of headaches. I just think if in some universe it were to happen, it would necessarily go along with a switch to 24h time.
You can say 15:05 because you know it's the afternoon and so 3:05 translates to 15:05. Now think through how that works when the whole world is on a single timezone.
