Ok, not a 'must' but a worthwhile inclusion in my opinion. As an example of where I feel it could be beneficial is in a thread that doesn't necessarily elicit a continual response from other members - like for example starting a 'conversation' in your Coffee Connoisseurs Forum showing off some WIP pictures of a custom coffee grinder that you are building. It may only get a few text responses and maybe only 25 'likes', but with all your pictures posted there it may have over a million views...
I don't know, that data seems important to me for certain types of posts - so while not 'critical' in the extreme sense, still pretty standard and worthwhile data to allow users to see..? Certainly as important as showing the chronology of a conversation.. is stating "3 MONTHS LATER" in a grey bar in the middle of a conversation a must, is the time-stamp not enough?
But yes, Extension probably makes most sense 🙂