kato

Or other rear echelon troops.

The Airforce and Army logistics turntables for Iraq are located in Germany (Ramstein and Mannheim, respectively). All flights to Iraq get refueled somewhere over Western Europe, or land there.
Soldiers wounded in Iraq are evacuated to hospitals in Germany (Landstuhl and Heidelberg). The overall command center for all NATO ground operations (like ISAF) is in Germany, as well as the coordination command for US Army Aviation through half the world (both in Heidelberg - 7th Army and V Corps commands, also LANDCENT and AFOD). Grafenwöhr is a major US Army training site - one of the main sites for pre-deployment live-fire training.

Well, Korea has been explained.

Without these (approximately 40,000) troops in Germany, power projection operations throughout the Middle East would immediately collapse. It's not just a matter of "getting there faster" - the US would have significant problems (to the point of "not possible") supporting any operations in the Eurasian hemisphere without permanent forward bases like these.

And Ramstein isn't the only one. Without Mannheim and its associated logistics bases, there wouldn't be any ammunition or spare parts for Iraq. Without Landstuhl, some 15,000 wounded so far would have had to have been evacuated to the US instead. Without Vicenza and Aviano in Italy, the 173rd Airborne Bde would have spent quite a bit longer than 5 hours in their planes when opening the Northern Front in 2003.

Contracts with Germany? Do you realize that Germany is not the one benefitting the most from these (see above)? Do you realize Germany actually pays operating costs for these bases (due to occupation rules) and employed several thousand soldiers protecting these bases in 2003 when the US lacked ground forces?