5. "He is ordering you to surrender this weasel"
Consider this: "Star Trek III" has the crew disobeying orders, physically assaulting Federation officers, humiliating one by locking him in a closet, stealing one starship and sabotaging another in order complete their mission. And yet, you are rooting for them all the way! You are even getting a chuckle out of it. But we know why. Because we want them to find Spock and save McCoy as much as the heroes do. But senseless Starfleet bureaucracy won't even consider them doing it. Kirk sums it up when he says, "The word is no. I am therefore going anyway". The theft of the Enterprise is just plain awesome. It gives the secondary characters their long-over due moment in the spotlight. I mean, in "Star Trek II", Sulu and Uhura probably had twenty lines of dialogue between them. Most of those lines being "Aye Sir" or "No response". "Star Trek III" had them finally doing something important. Sulu taking down the security guard and telling him "Don't call me Tiny". Uhura easily overpowering "Mr. Adventure" and locking him in the afore-mentioned closet (where I am betting he peed his pants). And especially Scotty, having been transferred from his beloved Enterprise to the cool new Excelsior and using it to his advantage to sabotage the new ship. But not before muttering "Up your shaft" to the Excelsior turbolift. Granted, Chekov didn't quite have his moment, other than wearing that horrible pink shirt. But I like to believe there is a deleted scene where Chekov goes to get fitted for his new Starfleet uniform and says, "I hate the way they unflap!" and beams out in his pink shirt. Not to mention Chekov had more substantial scenes in "Star Trek II" and IV. And nobody wanted to risk putting Chekov in a situation where he would scream.