Another thing I like about TMP was its ending. There was the sense that our heroes had returned where they belong and we were set to enjoy new adventures on the final frontier.
But, alas, Harve Bennet and Nicholas Meyer nixed all that to tear it all down and gives us the characters practically ready for retirement. The kind of adventures we had known would never come again until TNG. And, of course, that was with a completely different cast of characters.
The emotional resonance of TWoK is one of the things they did very well. I don't like to criticise that.
However, I do lament that they never really capitalised on the second 5-year mission. We had a lot of merchandise at the time but we've only had a few novels, and a few short-lived comic series. I think an animated series on TV would have been great fun. If they made one now I'd prefer it to be set during this era unlikely though that may be. Tweak the uniforms by all means but the ship looked great, the whole traditional crew was together, and we had plenty of alien crewmen to mix it up. I've done a couple of comic stories on youtube and they were great fun - I really must finish that story off!