Not sure. I think it may have been because the script writers and director were trying too hard to recapture the sense of the original, which was written and directed in quite different circumstances.
Or maybe it was because the actors had all moved on and were different people themselves, or maybe it was just that the actor who plays Anna, who plays a crucial role in it, imho, was pregnant and spent lots of time feeling like shit and rushing off to throw up!
ETA Also, there was a lot of expressed anger in the feature last night, which was rarely so expressed in the original two series. It made for uncomfortable watching.