Hmm, "Tomorrow is Yesterday" and "Assignment Earth" would like a few words, with regards to what stakes were needed in a time travel adventure. One was just "oops, we ended up in the past, we gotta get home", and the other was "we're on a historical study mission,... who's this strange Gary Seven guy? And oh look, its Apollo 8 on the launchpad"
Voyage Home had higher stakes than either Wrath of Khan or Search for Spock. In Wrath, the stakes were basically just "stop Khan from killing Kirk"... ironically, Kirk didn't seem to give a damn about the rest of the people on his ship (other than Spock) who died along the way. Meanwhile in TOS, he was broken up over even the nameless red-shirts MANY times.
In Search for Spock, the stakes were.... finding Spock, and not dying along the way.
In Voyage Home, the stakes were THE ENTIRE PLANET EARTH. If we don't stop this probe thing that has already completely neutralized every single vessel and starbase it passed, the Earth will be DEAD. Meanwhile, it didn't insult our intelligence by making some cookie-cutter revenge plot, or shoving a "bad guy" in for the sake of having a "bad guy".... it didn't NEED a bad guy. It made us THINK instead of letting us turn our brain off. It made us go "Hmm, maybe, just maybe, this thing that we might otherwise think as an enemy to be fought is instead misunderstood, and we should find a way to COMMUNICATE rather than fight it. The yucks were just a side effect,.... and yucks were one of the best things about TOS. Ever see "Trouble with Tribbles" or "City on the Edge of Forever"? My gods, what were the high stakes in Tribbles? ... were there ANY stakes?
Star Trek doesn't always need a "bad guy"
This need of a bad guy is exactly why every movie since First Contact has had revenge as a prominent plot point, and new bad guys trying to be the next Khan, all while succumbing to the standard Hollywood formula of "just sit back, turn your brain off, and enjoy the film" THAT is what makes a disappointing Star Trek film for me. "ugh... okay... here's another bad guy. I bet he's got a vendetta against Earth and is gonna use that Thaleron thing we saw at the beginning to try and destroy it. Yup... there he goes. Oh look, here's ANOTHER bad guy,... who's he swearing revenge on this time? Spock? I bet he's gonna scream Spock's name at some point as he tries to destroy Earth too,... yup, there he goes. Who's this grumpy Admiral guy? I bet he's obsessed with war, so he's gonna try an assassination in order to keep war going, just like last time.... yup, there he goes"
This obsessive need for having a "bad guy" is what is disappointing with Star Trek. Star Trek DOESN'T need "bad guys" to fight. What it needs are mysteries to be solved and questions to be answered, it needs adventure and fun, and it needs opportunity for every cast member to shine rather than just being background "course laid in, Captain" or "Hailing frequencies open"... and thus far Voyage Home is the only one to check all those boxes.