Well, I think it's also possible that people sometimes merge TOS Shatner with older Shatner, since older Shatner was heavier.
On the topic of shirtlessness, I think sulu was all right, too.
Can't recall seeing McCoy topless.
Semi-off topic: I just watched Kid Monk Baroni
with the audio commentary, and the movie is worth it just for the scenes where Nimoy's character stands around shirtless, looking in the mirror and checking himself out.