Hard tight fist with proper bone alignment, or a relaxed slapping loose strike? Would I rather get hit with a strike from a hammer or a whip? Which would I rather have in my atemi toolbox, and do I really have to choose.
Phi is hella right, I'd rather touch the wife (mine, Phi, not yours, although I am certain she's lovely) than punch out some Joe. I train for life, not live for training.
I'm sure most of us would rather avoid an altercation when that is possible. Sometimes, in a life-threatening situation, one does not have the choice to avoid it (even by running). Including atemi in your aikido is a good way of trying to preserve your life and possibly your family's/partner's - and therefore "training for life".