I think the sample size (three episodes) is a little small to make any generalizations. Dawidziak points out that there are some things about the episodes produced by Richard Alan Simmons (Bye-Bye Sky High, plus all the season 7 episodes) that makes them stand out from the earlier ones:
(1) It becomes clear to the murderer right away that Columbo is a serious threat - he spends little or no time being a funny little man that the murderer figures will be no problem.
(2) Columbo talks more about his past - in specific detail.
(3) The murderers have more defined back-stories; we learn more about what made them the people they are.
I don't know if the Simmons episodes are really all that different from what preceded them, but I find Dawidziak's thoughts interesting.
I thnk I'd murder a dozen business partners to keep the Samantha Eggar character in those silk robes. Besides, I don't agree that the main character was a jerk. Theodore Bikel made him much too sensitive, especially in that last scene. The look he gives, when he realizes he's incriminated himself, almost makes you want to cry.