^There were instances of planetary genocide in TOS, such as "Operation: Annihilate!," "The Changeling," and "The Immunity Syndrome." It's just that it was mostly offscreen, a disaster mentioned as already having occurred before the episode began, so the consequences weren't really felt. Or just after the episode, as in "The Empath" -- remember, there were multiple inhabited planets doomed by the supernova and the Vians could only save the population of one of them. So yes, there were billions of lives lost in TOS, just not Federation lives.
Not to mention the huge losses that Starfleet suffered in the second season -- the crews of Constellation, Intrepid, Excalibur, and Exeter all wiped out, plus numerous casualties on Lexington, Hood, and Potemkin. And then the loss of the Defiant just months after that. Starfleet was really hit hard in a short span of time there.
Indeed Christopher, I was being thoroughly ironic in asking about death in TOS, since there was such a high deathtoll in that series
I think Trek (especially 24th century Trek) is overdue something light and fun, to break up the near-constant stream of threats and chaos and destruction.
A spiritual successor to J.M. Ford's How Much For Just the Planet? would do nicely - although I fear (perhaps groundlessly?) Pocket may see publishing such a book nowadays as a risky proposition.
I think 24th century Trek rarely managed to do an entirely comic episode well. Ford was playing to rather more successful tonal diversity of TOS, which could manage farce much better. But the farcical and the overtly comedic in 24th Trek usually didn't work because the shows weren't so good at comedy, and the overly funny episodes seemed so tonally dissonant from the remainder of the series, as well as usually not being written, cast or directed so well. Sardonic and ironic humour was perhaps more suited to those shows, but they weren't very funny