Wikipedia tells me it was come up with in 1923, long after both global trade and the industrial revolution. You need all the countries to agree on the same calendar system or commerce is really hindered. It was way too late to change in 1923.

The French tried to change the calendar to something more sensible and closer to metric after the French Revolution. It did not last long.

Things seem to work just fine with the calendar we have anyway.

Also, it could be worse. The Mayans had three different calendar systems- a solar calendar, a lunar calendar, and a 260-day calendar which we don't know the origin of, but I like Dr. Ed Barnhart's theory that it's very close to a human gestational period.