Just had a Thief come into town just before the last vendor died.

It looks like the thief won't appear unless a new vendor gets recruited, making it impossible to complete the game until then?

(haven't loaded the latest patch yet -- and didn't see these in the patch log)

1 - Some monster-statues make noise when attacked. I think.
2 - Cavern has town mod "Mushrooms" but all I see are crystals everywhere...they do obstruct vision. There are very few if any mushrooms on some of the levels, but not all of them.
3 - ___ has been killed. ___ was keeping the hordes out of control. (turned in quest) You win. -- seems to me that killing X if s/he were keeping the hordes under control should spawn some type of "get hordes under control" quest? At least I always expect that...
4 - The happiest person in town (happy 23) says the town is doomed?!? (and similar depressing messages)
5 - When my Demon Hunter uses Demonic Control on an Ice Trap Tower (and other towers) they follow me....sliding across the ground. Should that even be a valid target?
6 - Perhaps skill icons should be red (i.e. "no valid target") while the cooldown timer is ticking. It's hard to tell when there's a hairline of timeout left through the corner of your eye.
7 - Things NPCs can say: Explain the Town Lottery. Hope to win the lottery. Critters got into their food again! They like their new __donated item__.
8 - I like the SIMS-like NPC relationship building. Seeing them talk to each other is cool.
9 - How do you stop a fight in town? 1 person did something wrong, people started hating her, the weaponsmith attacked her and then killed her -- and I lose my reputation?!? Should I have attacked the weaponsmith? Or should I have helped him kill her? :)
10 - When the naughty townsperson died, their husband wasn't upset?
11 - I haven't had a chance to study this but my son said it looked like townsperson $ quest rewards are being rewarded to the townsperson NOT to the character.
12 - Lure: I can't walk through my own lure, and I can't target my lure with normal weapons/bows. Thank goodness my Immolation Trap can kill my lure, because I could end up trapped in a tight hall. I think we should be able to walk "through" them like we can other summons, rather than having to kill our own lure to get past it. It's a bloody ball of light! :)
13 - I couldn't solve a rescue quest until I realized a nearby Lightning Totem counted as a "monster nearby". ooooh what a scary dangerous monster!
14 - Someone in town was starving. I "Failed the Quest" (and lost reputation) because someone else in town paid it off. Shouldn't that just obsolete it?
15 - just a funny: After completing a town, the quest came up to collect a Lost Soul's vial of essence. "I don't really need any more vial of essence, I just really hate lost souls." Someone has a sense of humor....

I think the idea is that Monster X was a peacemaker, restraining his species from fighting another mob species, freeing both species to focus on menacing the town.

It's even funnier when you get this and are asked to whack a totem. He couldn't maybe hire a lumberjack?

This is a bit of an issue with the NPC personality system. It wasn't really built for the happiness meter. Instead, NPCs are given personalities like pessimistic, optimistic, mean, nice, religious, superstitious, know-it-all, adventurous. These are set per NPC. I think pessimistic/optimistic and mean/nice should depend on the happiness level ie. they should be dynamic, while the other ones can be static per NPC.

It is harder for a pessimistic person to become happy compared to an optimistic person.

From what Bluddy and Shadow mentioned, maybe the townperson was that crazy guy standing on the corner with the "sky is falling" sign. So he is happy that his doom-saying is finally coming true! I can't find who said it originally, but only a sadist would be kind to a masochist. :D