Might be revealing a profound misunderstanding, but isn't that just because of the reference point? If UTC+0 were the The Chatham Islands, then a few would.

And then there would be a gap at 45. The point is that only three of the four quadrants are occupied.

Yeah that isn't covered by what I said. I wonder if it relates to convenience. Having the same time as your neighbour is probably more handy than having a day that is off by 15 in my opinion, even off by 30 wouldn't bother me much. There must be countries that have muddled through this scenario. But it still leaves a question as to why only certain time points are chosen and others avoided.