So I looked around but I couldn't find an answer to this..
Will the clock be optional? Can one choose to display it or to not display it? Personally, I much prefer playing without an in-game clock. That way I don't need to be too aware of how many hours I'm wasting The idea of a permanent clock on display in-game isn't a very appealing one for me, in fact I'm not entirely sure why it's being added at all.
The initial placement they were looking at was the clan chat tab, so you’d only see it there. I did see on Twitter that Mod Maz was exploring allowing it to be elsewhere and I presume there would be a toggle for that if they do go that way.
The purpose of the game clock was to assist with community groups who like to schedule events and the like with having a common time to reference. By using UTC, they can tell their groups an event will be at that time and everyone will be able to use that clock to know when it will be. Time zones can be a pain to convert sometimes, but game time in UTC never changes. It did pass a poll with more than 75% of the vote.
It’s no different than there being a clock on your computer, so not sure how that would affect how much time you have spent ingame.