What's the deal with the Kirk/Decker dynamic in The Motion Picture?

According to dialogue in TMP, Kirk selected Decker for the position of Captain of the Enterprise and even told Decker just how envious he was. Then Kirk fights his way into the center seat of the Enterprise and (in my opinion, fairly rudely) kicks Decker to the side. Then Kirk begins to demonstrate his dangerous unfamiliarity with the ship and comes off as incredibly arrogant, endangering the ship and the crew with his unwarranted overconfidence. The rest of the plot is chiefly moved forward by the smart thinking of Spock and Decker and not Kirk's doing. (Spock revealed many essential facts with his spacewalk gambit, and Decker gave the ultimate sacrifice by merging with V'Ger.) By the end of the movie, I was left with the impression that they would have done just fine without Kirk and that Kirk was being a real jackass for selfish reasons. If anything, Kirk may have hurt more than he helped.

Decker came off as an eager, knowledgeable Captain who willingly gave his life to save Earth, and Kirk came off as an arrogant jerk who was looking out for #1. Decker really was the hero of this movie.

Was this what they intended? I've always been confused by this. Maybe I'm just taking it the wrong way but I always felt like Kirk was a real shithead in this movie.