^I feel the same as Christopher. Spock's growth in the time period leading up to TMP, and directly after it, are key. Forgotten History did a great job of exploring the differences brought on by TMP. Whenever I see another 5YM book come out, it just makes me think the story is going to be all about the action or "planet of the week" and that zero character growth is to be expected. It's too bad Greg feels like this. I'd love to see him add something to these characters instead of telling stories where everything gets put back in the box at the end
Personally, it's because of the "put the toys back in the box" thing I like about TOS books. Sure, game-changing events that shake up the status quo have their place and are fine enough, but that's basically what all the 24th century series novels are these days. It's nice to take a break from that and just have a stand-alone story which gets wrapped up at the end. As it is, TOS was for the most part planet/alien of the week, so the novels taking this approach makes it feel like an authentic episode.
Hell, I personally don't think it would hurt for the 24th century novels to do something set in the TV series timeframe. Sure, we all like catching up on the machinations of the Typhon Pact, and that's obviously working out for Pocket, but I'm sure there could be room in the yearly schedule for say one TNG novel set during the TV series run. I'm sure there must still be enough casual TNG fans who would dig a new novel that didn't have a bunch of new characters and ongoing storylines that have a few years of backstory to them.