Why do you think it's overrated? "The Trouble With Tribbles" is the best of Trek TOS's few overtly comic episodes, IMHO. Do you think it isn't funny?
That's the point.
If you like the TOS comedy episodes (I don't)---it is the best of them. So in that sense it is NOT over-rated.
But I guess if you enjoy the comedy episodes and don't like TTWT--then it IS over-rated.
I enjoy it more than 'I, Mudd' or 'Piece of the Action'