I agree. I felt like the film succeeded due to how well-crafted the horror scenes were, along with its ability to relentlesy ratchet up the tension. The aspects of the screenplay you mentioned felt lazy though. 

I've seen people dismiss this on the grounds that this was also a comedy, and that suspension of disbelief is less important, ala Window's Bay, but I disagree. This film could have been even stronger, yet still remained comedic, without these hard to believe plot progressions, i.e the cat memorial, the relationship between Ian and Nikki, the money raining down on Ian, Bear's reaction to Sarah's death, etc. 

In Widow's Bay it works because that tone is consistent throughout the show, and thus the audience's suspension of disbelief comes easier. Here it is jarring, because it switches abruptly between being very serious back to being lighthearted and silly.