Moods dont make dwarves go nuts by making them less happy. The game just flips the nut switch after the dwarf fails to make his artifact for a certain amouth of time.
The only way I see to keep the game a 'sims' violence level is to:
Keep population below 20 (which prevents moods entirely),
Turn of temperatures, to mod out all weapons, trap components and weaponmaking professions,
Remove or pacify all otherwise hostile creatures,
Add a lot of damblock to prevent them from falling to their dooms (though im not sure if that works),
Add innate swimming,
Give the dwarves some [NOsomething] tags for the thing that still causes them to die.
As for happyness, adding [NOEMOTION] would prevent them from going mad, but would also make them completely apathetic to everything happening to them. It shouldnt be needed with the dwarves having no deaths to go mad about.
They would of course still die from starvation, dehydartion, chasm falls, atom smashings, etc. But well, sims starve too. And those other death arnt all that bloody
Though its not like im saying this to help the OP, probably amongst these 12 pages this all got mentioned plenty times allready. I just found it interesting to think about. Its probabaly why this thread is as long as it is.