Because there's little other reason to watch this movie. I didn't care about the characters and I don't understand why any of these people are friends, except for the two women (the Scott character is particularly irritating).
The actors did their jobs capably. Eliza-Jane Morris was very strong, as was Lindsay Ashcroft. The actors playing the parents were fantastic despite limited screentime. Nate Bryan and Billy Chengary were adequate. I don't blame the actors for their performances--I think they did the best they could with the script they were given, though neither is a stand-out for me simply because I loathed the characters they played.
Joette Waters is phenomenal as the shop keeper, totally deserving the "and" credit. She makes the absolute most of her screen time and is a joy to watch. I wish they had done more with her character.
Yes, the special effects are amateur, but I expected as much going in, so I don't count these against the movie.
Some will complain about the preposterousness of a killer pinata. Honestly, that was one of the few things in the movie that worked for me.
This probably would have worked better as a 30-minute short.
Horror fans hoping for T&A will be disappointed. There's very little.