Why did Germany nominate a dictator?

Well, "Germany" didn't really. Hitler more or less appointed himself, by a series of devious political maneuvers.The President of Germany at that time appointed the Chancellor of the Reichstag (similar to Parliament or Congress). This was a time of turmoil, as the Great Depression hit Germany particularly hard and the Weimar Republic had recently gone through one of the worst bouts of hyperinflation in history. With the economic turmoil came political unrest, and several...

Well, "Germany" didn't really. Hitler more or less appointed himself, by a series of devious political maneuvers.

The President of Germany at that time appointed the Chancellor of the Reichstag (similar to Parliament or Congress). This was a time of turmoil, as the Great Depression hit Germany particularly hard and the Weimar Republic had recently gone through one of the worst bouts of hyperinflation in history. With the economic turmoil came political unrest, and several factions---including the Nazis---vied for power over Germany. Out of this came a tightly contested election that ultimately ended up electing President Paul von Hindenburg (the ill-fated zeppelin was later named for him), a moderate war hero that nobody particularly liked but also nobody greatly despised.

Initially Hindenburg appointed someone else, Kurt von Schleicher, as Chancellor. Schleicher was anti-Nazi, and wanted to establish a more moderate republican government. But Hitler would not have this, and circulated a rumor that Schleicher was planning on killing Hindenburg and usurping power (it's unclear whether this was actually true or not), so Hindenburg removed him and appointed Hitler as Chancellor.

Then, after Hindenburg's death, instead of holding an election to replace Hindenburg as he was supposed to do, Hitler appointed himself Fuhrer---dictator. Before the decade was out, Hitler invaded Poland and began WW2.

Due to the tumultuous situation, conditions were ripe for radical change; but Hitler never actually won an election of the majority of the Germany people.