Why good? The point is the Germans realised that their local bees were crap and did something about it.
Here's a little history for you.
In 1857 Emil Ravenegg Rotschutz sent bee colonies from Višnja gora, (Was Yugoslavia) Carniolan province, to Eichstadt, Germany. The experiences of German beekeepers with bees from Carniolan province were so good that they demanded more and more of these bee colonies. News of the gentle character of the grey bee soon spread to other nations.
In Central Europe the aggressive dark species, Apis mellifera mellifera, was endemic. Soon new branches of beekeeping business were established. Following this new activity in beekeeping, beekeepers reoriented their bee management into the production of additional bee swarms. Honey production became only a sideline product for some beekeepers (Rihar 1998). Public opinion from that time supported the attitude of Slovene beekeepers: “we are the breeders of Carniolan bee and we should be proud of our bee”. Native bees really penetrated in the subconscience of the beekeepers at that time.
Between the period from 1857 and the end of World War I, it is documented that specialised Slovene merchants exported at least 170.000 swarms; according to some estimates the number is even as high as 500.000. In many places they completely superseded the native dark bee. Today, their work is being continued by honeybee queen breeders, who sell approximately 40.000 queens, mostly to the countries of Central and Western Europe, with exports increasing annually.