Actually Octavian cared about conquering Germany. He would have get that done, too, with no Teutoburg Disaster.
What you said about the roman conquests is not completely true, and especially wasn't under Octavian. He poured resources in "cheap" conquest of "underdeveloped" areas like Moesia, Raetia and Illyrian highland, probably in order to give the empire greater geographical coherence, let alone prestige. Those areas, essentially the entire right bank of the Danube, have been one the (relatively) easiest conquests of Roman history, but development came only later. Also, it could be noteworthy that only a tiny fraction of the areas conquered under August is Romance-speaking nowadays (while it was a little larger in Middle Ages). OTOH, Italy, Gaul, Iberia and Dacia are mostly romance (and in Spain, Vasconia was subdued under Augustus), and Dalmatia was.