It'd be poor of me as a developer to not readily accept and face critique when it's literally the only thing that can help you grow and get better. People that fawn over your work as a flawless masterpiece aren't going to help you improve, as much as it's always nice to hear you're doing a good job. :P
I'll admit this is a first that I'm hearing someone having such a visceral reaction in the negative to Path D. The only context I can give here is that the intention for a lot of the game (be it bad ends or instances of Tyson being flat out abusive) was to demonstrate how different people cope under stress and deal with traumatic experiences. Dave shuts down, Tyson becomes a rabid/abusive control freak, Orlando is a crybaby, etc. There are other things going on here too which exacerbate this further with Dave/Tyson having that pseudo family bond that makes feelings all the more complicated for these two. Dave shutting down and becoming more emotionally numb following the deaths on Day 10 is also why I went more muted with him interacting with Dean and Roswell.
Although this part stands out to me: "After day 7 the game switches. Oswald and Benson's identities are revealed, you no longer need to play detective to try and find passwords (except for day 10), and the power to save the characters is gone after day 10. " Given you already mention up to day 15, I'm assuming this means you've been able to find Path A/B, so I'm curious as to what led to this assumption here or if it's just something indicative of Path C/D.
As far as Dave's father and likability, how would you have rathered been presented with him given that he's dead by this point chronologically and we have to factor in narrator/Dave-bias in how he remembers his dad?
Part of what I had to do prior to writing the first treatment of Password's story was to talk to a couple of professionals to find out how trauma effects people as a whole and got some key notes on different kinds to potentially write about. In the interest of doing sensitive topics justice (such as suicide, depression and alike) I've been trying to keep that close to the notes I took of those interviews rather than write something that's closer to a TV showing of those topics so they'd be more palatable. A mistake potentially on my part given the demographic the game has attracted, but that's at least something that's been informing what you've been reading so far.
Thankfully a lot of the rest can be handled when I hit the editing stage.