I'd wager it's because shorter-term, more local maximums are easier to achieve, and are also profitable. So basically because of greed. More charitably, because

I'd wager it's because shorter-term, more local maximums are easier to achieve, and are also profitable. So basically because of greed. More charitably, because how people's resources like attention, ability to care etc are finite, and because the kind of high organization it would require to achieve such a goal.