The tone of the music of Star Trek changed dramatically from Season 1 to Season 2. Whereas Season 1 was subtler (as subtle as it could be being a science-fiction show in the 60's), and the title track itself definitely more sombre, Season 2 added a lot more unnecessary music in the wrong places, some ill-conceived "horns" flourishes and a needless "wailing woman" in the title track.
Fortunately I've only seen one episode of TOS: Season 2 so far so I'm hopeful. How long does the change last? Both the title music and the background score in the episodes? It's embarrassing.