[crAzerk]

I think the participants themselves have to somewhat get into the role.

Would be better if the roles had more space for individuation. But what you're thinking of is other versions of Mafia (e.g. SC2 Themed, etc. Just google it), it's quite hard to RP with just 'Citizens'.
Most importantly is they can't go inactive -_-

Well AFAIK, last round we had pikk0n typing essays every other day, another round we had myself playing randomly (inconsistent arguments, attention grabbing, etc) and got voted out by Citizens.. just that I was the Joker so i won, another round we had some long argument between myself and pikk0n,
And ofc some rounds had relatively intense 'last few votes'.

I think a problem is that the veteran players, after going through so many rounds, are getting bored of the monotony. There has to be new dynamics in the game besides 'stay under the radar for as long as possible and have highest chance of winning' which I can say is the best strategy everyone is using atm. THat's why I suggested a revamp with more active roles.