Shortly after NATO was established, the Cold War began and NATO became the balance to Warsaw Pact powers of the east, the WP was also established in 1955 mostly as a response to NATO admitting West Germany, and to once again keep Germany from re-militarizing.

So the mission of NATO changed once already for the circumstances of the Cold War.  Now, it seems, that powers that be, wish to change the NATO mission once again, displaying a geo-political level of what we called in the military "mission creep": you start out with one goal but is slowly morphs into longer and drawn out objectives that had nothing to do with the original mission.

I think that only makes the case stronger that NATO is obsolete and the EU can do with its own security forces.  It is strange that that fact isn't well-know, but if it were, the question of NATO's relevance may have come up a lot sooner when Germany reunified and the whole of Germany was a member of NATO itself, especially now that Germany has exercised military missions outside of its borders.

Someone correct me if I recall the facts incorrectly.

"Schiller sprach zu Goethe, Steck in dem Arsch die Flöte! Goethe sagte zu Schiller, Mein Arsch ist kein Triller!"