Why have converging runways?
Ramstein is a major US logistics airbase in Germany. Originally Ramstein used to have only one runway. The runway was built with fighter aircraft in mind and could also host C-130 Hercules aircraft. Bigger freight aircraft and passenger aircraft could not use Ramstein and were handled at Rhein-Main base, which was at Frankfurt's international airport.

When Frankfurt needed to expand their civil operations, Rhein-Main base was closed and all the US military tranport operations were transfered to Ramstein. In order to accomodate the big transport aircraft at Ramstein, the airport needed an upgrade. To keep the base open during construction works it was elected to convert the old India taxiway into a runway (08-26) which was made longer, wider and thicker that the original 09-27 runway. Also new aprons were added to the North and South of the runways. When the work was completed in 2005, the old runway was closed for reconstruction. It was then resurfaced and extended so that since 2008 there are two operational runways at the airport, so that in case of maintenance or an incident the operations can continue. 

There is no relation to launching fighter aircraft in rapid succession.