Funny. I had a boss who thought that use of initials was pretentious. Or maybe I'm putting words in his mouth and it was specifically my use of a middle initial he didn't like. Harry S Truman's name would presumably have given him a headache.
Either way, I countered that having a customised number plate on a car was surely just as bad, to which he had no answer.
I have 2 first names and I prefer to go by their initials. I’m so used to it that I sometimes don’t notice when someone calls me by my actual first name.