Re: TNG's "Too Short a Season" with Kirk...
True enough, but I still think the episode works better dramatically with someone in their 20s (or rather 30, the actor's actual age when the episode was filmed) trying to convince someone from his past he is the same person, even though he looks either younger or as though he hasn't aged at all. If it had been Kirk and Tyree (assuming it really was a sequel to A Private Little War) than even in his 50s Kirk would still look older than Tyree would remember him as and therefore would have less of an impact.
"Internet message boards aren't as funny today as they were ten years ago. I've stopped reading new posts." -The Simpsons 20th anniversary special.