I learned so much while reading this thread...and in fact it's now making me lose a lot of motivation to keep playing my current fortress, if this is what I have to look forward to.
I play the game in rare spurts and I think stress wasn't fully implemented last time I played. Because I like to use the Lazy Newb Pack and also like playing on the most stable releases of things, I'm playing on the 2018 version, without any tweaks that may have happened to stress in Villains. I realize that's less helpful for feedback but I felt compelled to post my thoughts anyway.
Early on I had most dwarves generally happy, as I usually was able to do in previous versions...though they weren't becoming ecstatic as they usually did. And I had one particular dwarf, who practically nothing had ever happened to, who was just miserable. Even as someone who uses the wiki quite a bit, I had no idea what was wrong with this dwarf or how to fix them. Their thoughts were full of "admired own fine bed," "slept in a palatial bedroom," "were satisfied at work recently." It really didn't indicate what the problem might be. And they started tantruming, and continuously "conduct meeting," which I learned was an attempt to scream at the management. I figured this particular dwarf's traits must've been a perfect storm of badness, so I let them starve in a locked room. (Old habits die hard...forgot you could exile.)
Except after reading this thread, I've looked through some other dwarves' personalities, and they're all getting on that same road. Personality changed for the worse after getting caught in the rain once several years ago.
Someone else started dipping down into the yellow, again for essentially no visible reason at all in a fort full of wonders and peace and good food. This time it was a longstanding skilled dwarf I was kind of attached to and didn't want to lose. I tried many things to fix their stress but it didn't seem like anything could really reduce it. I locked them in a room with the expedition leader in an attempt to force them to yell at each other for a while, but they both just stood there with no job. Didn't know what to do. I ended up targeting the dwarf and typing remove-stress into DFHack, but even so I regret it. They immediately shot up into the ecstatic range, and are essentially a drooling lobotomized happy dwarf. It felt so artificial.
But reading this thread, it sounds like that's the only recourse. Gotta remove-stress -all, or edit the raws to reduce/remove the effects of stress, or do both. But I really don't want to have to do that. I already customize the game in a few ways to my liking, such as limiting to 50 dwarves at the moment, but this just feels so cheaty, and not what's intended, and certainly damaging to the individuality of the dwarves as characters. But on the other hand, I don't want to have to deal with dwarves losing their mind all the time for no good reason; no good reason from my point of view of course, I personally don't think being caught in the rain once is cause to become a bundle of nerves ready to explode at any moment. That may be how dwarves are, but if that's going to be the case moving forward, then the game is going somewhere that I can't follow.