In regards to the OP's question, no. Huge obvious bugs notwithstanding, your playstyle has always had a much bigger impact on the wackiness level than the game features. I would say that all these years of development have gradually made the game operate less and less on video game logic (put a waterfall in your meeting hall and the happy thoughts will make it literally impossible for any dwarf to ever become sad!) and more and more on, if not realism per se, the internal logic of the world (regular civilians are traumatized and might even experience mental breakdowns if they're exposed to the horrors of war, but part of military training involves raising the Discipline skill which lets soldiers potentially fight to the death in defense of the fortress). Because there's more variety among dwarves, you could argue that it's actually more chaotic in a way, not in terms of slapstick violence breaking out because you accidentally melted someone's stack of masterwork bolts, but in terms of unexpected consequences for your actions, like if a soldier who becomes completely helpless in stressful situations freezes up at the wrong moment in battle. But even in terms of slapstick violence, you can now set up a tavern full of booze, goblets, and Tavern Keepers, give your dwarves nothing to do for a month or so, sit back, and watch your citizens pummel each other senseless and drink themselves to death.
I think a lot of the really silly stuff that happens in the game has always just been due to bugs that are bound to be fixed sooner or later, so if you're used to the glitches in older versions and then they get sorted out, it might seem like things have changed significantly.
As far as the stress system is concerned, I'd really like to see more effects from positive experiences, or any, really. At the moment becoming a parent is pretty much the only thing that seems to have a lasting impact on a dwarf's personality that doesn't involve tragedy, horror, losing their clothes, or being rained on. It would be nice if, for instance, dwarves in leadership positions could potentially use their leadership skills, assuming they're good enough at it, to permanently shore up the more troubled dwarves around the fortress, beyond just spamming Meetings endlessly to no effect. Or if making friends and being reunited with rescued loved ones permanently made them more cheerful or more resistant to stress or whatever. As it is, dwarves' thoughts seem to revolve mostly around seeing dead bodies and getting caught in the rain, and the effects seem more or less random; some dwarves become volatile time bombs waiting to go off at the slightest provocation, others get rained on one time and instantly fall in love with nature and become impervious to all stress forever. Positive thoughts currently don't seem to have any meaningful effect whatsoever--a dwarf can go from -1.0m stress to freaking out at the same rate as one who starts from -0 stress.