So I followed this game front to back, although as a non-participant my perspective of the game's events will likely be incomplete.
Sigh... *rolls eyes at lazy town* I gave you the PoE before I died! 
I'm going to be a bit more blunt here - what I see is that after rob's efforts, and a few other players', town should have won. Instead, as in many recent mafias, all mafia had to do was pick off the active players and everyone else disappeared. More on this later.
I feel this mafia was fairly unbalanced in favor of the mafia. The ability to steal items that ruin the ability to lynch mafia members and items that kill people instantly is entirely too powerful. Town stood the best chance this game if they used these items in night 1, in all honesty.
Upon the game's start, I believed mafia's chances were roughly 55-60%, with the sway being for the reason you stated.
Inactivity also hurt this game a great deal. I think something should be done to lessen the amount of inactivity in future games.
Agreed. I'm strongly in favor of modkills for inactivity being a more common rule here. As said above, town has lost far too many games recently just due to lack of activity.
For me, one of the main reasons of being inactive was the fact that I was a vanilla. As a mafia power gamer, that feels like you're worthless and just there to be lynched at some point. I tried to circumvent that with role madness in my mafia, but that is pretty much guaranteed to be imbalanced.
Do other people feel the same way about vanillas? What should we do about it?
I hate being vanilla. I would rather be literally any role than vanilla, even if it would be detrimental to my team, myself and my playstyles, etc.
Having said that, even if you are vanilla, you do have a job in the game. Your job is to use logic, intuition, and reasoning to find mafia and win the game. Players should be doing this, at least at a basic level, regardless of role, vanilla or otherwise. Using your role should only be a small part of the game - most of the game should be finding the mafia by deciphering scumtells and using deductive reason.
If you feel worthless as a vanilla, you're ignoring a core part of gameplay.
Also, vanilla roles are a vital part of any properly balanced mafia with certain investigate roles. Mass roleclaims are the only thing even remotely close to inactivity in terms of detriment to the average quality of play in this community. I'd argue it's worse.
Vanilla roles aren't really an issue here at all. It's a scapegoat for the real issue...
Giving roles to everyone seems to be the easy solution to this. It might be imbalanced, and there needs to be a way to protect mafia from a mass roleclaim, but I guess it already became the culture for our mafias. I want to try hard in the next mafia to incite more activity, as one more try to see if we can run a game with a lot of vanilla (if that's the case for the next mafia).
...the culture of mafia here badly needs to change, anyways. In a lot of the recent town losses to inactivity, it's because mafia kills the hardcore players, leaving casual players to finish the game. The gap between hardcore and casual feels really deep, and a lot of the issues here stem from it.
I think that's a fundamental issue that a few fixes might help with, but they won't change entirely. The
people need to change - we have to get everyone on the same page as far as what the heart of mafia here should be. Either the people who play casually need to leave, or learn to play more in depth, or we need to decide that mafia is more casual and build them as such, or some compromise of the two. That's a long-term solution but I think it's needed.
Edit because game is over anyway: I found it weird that Ginyu was not straight up lynched after Solaris claimed.
I agree. From my perspective, that was when the game shifted strongly to mafia's advantage.
