The time they chose is the most reasonable. It's not a weekend, so anyone getting up early is doing so for work/school. Keep in mind they have to consider the whole of the U.S., which is 4 time zones. If they did the server work at 3 am eastern like you said, people on the west coast would have the game go down at 11 that evening. That's a major bummer for people who have been working all day.