^It's not the only reason I don't like the episode, as I found it overall kind of boring. It was just an extra observation.
How can it be an "extra" reason if it's the only reason you cite?
But I get what you're saying. I watched it a few days ago as well, and it's less action and more murder mystery, and I thought the twist at the end was neat, if poorly executed. I don't think it's one of the show's stronger episodes, but I also don't think it's one of the worst.
As for Trials and Tribble-ations, it was a tribute episode for Trek's 30th (I think) anniversary. That's what made it necessary in comparison to Who Mourns for Morn, which is part of a very uneven season 6.
I guess I'm a little confused by what you define as "necessary" in this context then? As I said, it was a fun romp of an episode, sandwiched between two very 'heavy' drama episodes ("Waltz" and "Far Beyond the Stars"), so I'm just curious about your reasoning?