A dead Townie, by definition, can't help the town anymore. There's everybody else looking back at their past words, sure, but most of us don't do that nearly as often as we should. So what it comes down to is that everybody wants to feel like they've helped in some way. Most players would rather be something like a Radiant or Gremlin. At least then they feel like they COULD do something useful, even if they're instead doing nothing or hurting the town most of the time. So I think what we really need are more weak-ish roles for the town. The Xylbot Watcher is a perfect example. It's knowledge, but it's not going to win the game or clear someone on its own. You need either a non-matching claim, another player providing more information, or a decision based on the day-game. The first one's pretty frequent (although would happen less often in a forum setting), the second is really rare, and the third would be a good thing. That's all not even considering that the result might actually prove nothing, but even then, the player would think "There's always the next night and the day game to catch scum".
Say, we should run a Dephy (or is it Dethy?). It could get pretty chaotic and thus fun! If you need more variant cops, lemme just throw a bunch out: one that reports a faction the player is not (Player X is NOT neutral); ones that report all townies as mafia, all mafiosos as neutral, and all neutrals as town; one that inspects two people and reports their alignments, but not who has which one; and of course combined roles such as a cop roleblocker or cop doctor. Anti-town roles include: a combined cop serial killer, a miller, a godfather, a frame artist, a mafia guy that makes his target naive or paranoid, a guy where his alignment shifts to match the inspections on him (neutral should be sk, mafia should be mafia-ally, town should be a townie, all with no actions except the sk who can kill), and just for kicks, an sk that can hide an unlimited number of times and randomly turn someone into an Ascetic in addition to killing or hiding.