Going down that route though: You are right, that this stuff is completely arbitrary and probably a heritage of some sorts. But it's deeply ingrained.
Imo:
The world would be a better place if everyone would drive on the right (haha!) side. Why don't we fix it overnight?
The world would be a better place with only one (and simple) calendar. Go ahead, propose one.
The world would be a better place without discussions about date and time _formats_. You know how much these cost?
The world would be a better place without different units, depending on country. Can we please drop feet and whatever other body parts were used? It's "historical baggage".
The world would be a better place if we had just one country with one legislation and one global set of rights.
(Obligatory link: http://worldtimebuddy.com - which I found through this site - is regularly the most awesome utility the web has to offer for me) See, I don't really disagree with you. But you're a dreamer if you discuss about whether we really should depend on time zones. And in my book a couple of issues are more important to fix before we tackle that problem and introduce a stardate of some sorts.