I don't disagree with any of that.
But at the same time there are many things in the original film that are contrived, unconvincing too yet nobody talks about it. Like, how they got all their equipment?? They went from being fired to having these spectacular neutrona wands, a containment unit for ghosts we don't know how it works or how was it made, where did they get all the materials to create the ghost traps... etc etc. We don't mind because it's a quick route to them becoming Ghostbusters, we just accept it as it is.
That's exactly what I did with Afterlife too. There's a huge gap in time without Ghostbusters, there had to be a reason why they were not doing that anymore. And with a main character gone, there wasn't much left for them to do than to explain it some way. I'm willing to accept the contrivances because in the end there's an emotional resolution.