After all the point of NATO was to "keep the Americans in, the Russians out, and the Germans down"
https://www.reuters.com/article/us-eu-agenda-idUSKBN0FB06B20...
It's been going on for far longer than that and pretty much since the late 1940's.
And while Brandt was eventually replaced by the more conservative (but still social democrat) Helmut Schmidt, the general strategy of mutual economic dependency was upheld, and contributed to the eventual reunion of both Germanies.
In general, back then this strategy worked so well, that even the chancelors from the conservative CDU didn't feel compelled to change it.
Even Merkel, while far more cool and restrained towards russia than her predecessor, did not really change much in that regard. Kinda expected from a conservative though...