Predictability for travellers. It's helpful that no matter where you are, one has a relatively stable point of temporal reference to sunrise and sunset.
Most of these states are motivated by ridding themselves of DST. Shifting time zones is just a byproduct here.
The benefit of time zones (that roughy correlate to local solar time) is that I can get a good idea about their day without any other info; (1am they're probably sleeping, 12pm they're probably at work but might take lunch). If I need to convert between time zones I use my handy lookup table that any computer/phone or back of the envelope math can do. If I want to have a meeting at 1pm in some new fancy Internet Time I have to do some gymnastics to figure out if my friends in India are even awake, let alone working. If I'm flying to Japan and my flight lands at 6am Internet time--should I find my hotel to sleep or go watch the sun rise?
