Why Daylight Savings?

Why do we have daylight savings time? It's one of those emperor-has-no-clothes questions. Why does it matter if darkness creeps up on us faster in the morning or in the evening? Is this related to some puritanical ethos that says that waking up early is good for you? Is it an idea that having some daylight around in the morning while you're working is more important than having some daylight around in the evening when you're at play?

Am I missing something?