I mean they opened fire upon a BOP as soon as it de-cloaked without actually waiting to see whether they armed their weapons or tried to establish contact.
I swear, do some people actually watch the movies...
The Search for Spock said:SULU: Klingon Bird of Prey, sir! She's arming torpedoes!
That line was given as the ship decloaked.
What exactly would be Kirk's reason to wait and communicate with the Klingons? They are unable to contact the Grissom and the Bird-of-Prey is arming weapons as she's decloaking.
Woops! It's seems that I forgot that particular piece of dialogue.
Of course, my problem with that scene is the fact that Kirk doesn't immediately raise shields (torpedoes would be useless against full strength shields) as the BOP decloaks, in fact why didn't Scotty or Sulu (who were pretty much handling everything except comms and science) have one of their respective fingers on the shields button during the whole "is it a cloaked ship or a subspace distortion" debate?
Anyway, it just adds to the idea that Kirk and co. weren't thinking clearly, it was only a few weeks ago that they were caught out by not raising their shields at the first sign of trouble. The worst thing that could have happened was the shields would not raise and everything would go to hell like it did anyway, the conversation with Kruge would still happen (because of his ego - "take prisoners, screw the usual practice of destroying any and all enemies") and the Enterprise crew would still formulate the self-destruct plan - again I refer you all to the incredible missed opportunity that they had to beam the entire Klingon crew to somewhere where they wouldn't be a problem like Space or a volcano on Genesis, or perhaps the Enterprise brig? (for those of you still convinced that Kirk and co. were doing things the "Starfleet" way, despite the fact they all decided to murder most of the Klingon crew by blowing up the Enterprise).
It's really out of character and we all know that the reason that things went this way was because the Enterprise needed to be destroyed and somebody felt that Kirk and the villain needed to have a physical encounter because it was absent from TWOK.
In terms of the morality of it all, Kirk did say that to Kruge that "your presence here is an act of war" where the usual rules don't apply, he was also left with a clapped out starship a limited crew with an average age of 50 and plenty of reasons to believe that they would all be executed upon allowing the Klingon crew aboard. With resources limited, a hostile force about to descend upon you and the very real possibility that your life and the lives of your friends are about come to an end - you would jump at any opportunity in which to break out of this predicament. It just so happened that Kirk ignored the first and most obvious opportunity (and easily the most efficient).
One, it's not a crime to attack someone who clearly is going to attack you. Two, there were five of them on the ship. Getting into a shooting match wasn't the ideal choice. Kirk made the right move by luring them into weapons range and getting in the first hit when they decloaked.
If the Klingons were there peacefully they wouldn't be cloaked, they wouldn't destroy Grissom, and I honestly don't see how you can defend them not being treated as the villains they were in this movie.
As for your suggestion of raising shields? Did you not watch the movie? They tried that and they didn't work. The computer automation systems overloaded. Let's suppose Kirk did follow your suggestion. Not only would that have alerted the Klingons that they were detected, but if they failed the Klingons would have gotten in the first shot and crippled them. As it happened the ship running on automation was crippled anyways.