I think it was the last time Star Trek in any incarnation was a real adult drama.
Yes, I've felt the same way: with TVH bringing in the "comedy at all costs" everything got goofy and watered down, as if they had to make up for the aging cast and their expanding waistlines with Krazy Komedy Kapers. As much as people harp on TFF for its comedy, TUC has as much ridiculous humor and off character beats.
Star Trek III was the last time the original cast movies were taken seriously.
I have to enthusiastically agree about the score - brilliant!
It's fricking amazing and I nearly soiled myself when the complete score was released a few years ago.