Why did the ancient Greeks spent so much time building temples and worshiping their gods?
As far as the Greeks being excessive, the christian cathedrals and churches of Europe and the Americas are certainly numerous and opulent (e.g. The Vatican) and the mosques of Islamic countries and the Americas are in large numbers and just as well appointed. As far as devoting excessive time to worship, the whole economy of Christendom used to drag to a halt at least one day a week for sure and for dozens of special celebrations like Easter and Christmas every year. In muslim countries there are calls to prayer five times a day that stop all activity – business and otherwise – and the observation of the Eids causes massive changes in lifestyle.