That's a good point, Mike. I wonder, too, if in thinking that Chekov was supposed to be hip, Koenig is simply remembering what he wishes were true rather than what actually was the case. I mean, I watched TOS back in the day, and I never once thought of Chekov as "hip." Not even for an instant. Maybe he seemed hip to Gene Roddenbury or to Koenig. But GR was, let's face it, middle aged, and Koenig was 30 or so when he was on TOS, and while 30 seems pretty young to me these days, 30-year-olds were not the arbiters of hip in the 1960s any more than they are now. So their definition of hip quite possibly didn't really fit in with that of actual hip young people of the day. Not that I was one of them - I was too young to be hip. But I knew people were hip - heck, I knew actual hippies - and Chekov was never associated in my mind with any of them.
But then again, as I've mentioned before, I was always a Spock girl. Always. Spock is hip even though he never even tries to be.
Koenig, after all, was supposed to be a bubblegum sex symbol to us young female Trek watchers, and I don't think that worked out all that well either, though there were no doubt girls whose prepubescent hearts he sent all a-flutter. All I can say is that in my case, it didn't work that way. Maybe because of the "Spock girl" factor I mentioned earlier?