I think that these common decisions are the ones based on trying to prolong life another day, another week, in a terminal situation where the outcome cannot be changed even with extraordinary measures. The decision to terminate a healthy, but cognitively disabled person is not the type of decision happening every day--if it were, there wouldn't be court involvement every time a "loving" family member decides they're tired of waiting for the person to die.
I'm afraid there are lots of families who have relatives who are brain dead. Decisions are made to terminate life in those cases as well. Every day.