Are you saying that BONECARN should be a personality trait? That INTELLIGENT or CAN_CIV should be personality traits?
No, because those tags define BEHAVIORS. Personality traits do next to nothing at the moment. They trigger an occasional good/bad thought or allow a a dwarf to train "persuader" or other social skills and that is the extent of that.
The [SADISTIC] tag would define actual, programmed behaviors. Building skull thrones, tossing enemy corpses around, using body parts as impromptu weapons.
Those are behaviors, not personality traits. Again, in an "ideal" game yeah all those things could be controlled by personality traits. You can have an "inteligence" level that determines the civilization capability of a species, so higher intelligent critters build more cities. You could have a Immunity: FIRE scale that determines how protected they are from fire (completely, a lot, a little, none). You could have "Lock picking" attribute or a "Trap avoidance' attribute that determines the quality level of doors/traps that a creature could pick.
But a system like that is what, 5 years away? 10 years? WHo knows?
Right now, we have tags that define behaviors:
BONECARN
LOCKPICKER
MISCHEVIOUS
TRANCE
TRAPAVOID
VERMINHUNTER
etc. etc.
These tags define behaviors. The game is currently set up to read tags, not behaviors. Plus, what would happen if you wanted to put the sadistic tag on a creature without a personality? Say a demon spawn that is a fairly mindless killing machine. And last time I checked, only civs have personalities.
Trolls, which this tag is specificaly designed for because of the PowerGoal mention, do not have personalities. So until personalities are useful enough that creatures like Trolls, Ogres, and other non-civving baddies have them, this tag should not be a personality trait.
NOW, you could have a seperate sadism personality trait that would generate good/bad thoughts from inflicting violence, but that would be a HUGE difference from a creature that prefers to make a bed out of the crushed bodies of it's victims.