We spend a huge amount of our time talking about and reasoning about time. Destroying the meaning of all of the language we've built up is pretty significant.

We spend a huge amount of our time talking about and reasoning about time. Destroying the meaning of all of the language we've built up is pretty significant. More importantly, it basically ensures that all that terminology will be vastly different when you live in different parts of the world, where the day changes in the morning vs the middle of the solar day vs the evening vs the middle of the night. Weekday names will be entirely regional, and their implications will be as well.