The fewer wars America and Europe are involved with together, the better. Europe has the economic and industrial capacity to defend itself, and America certainly doesn't need Europe's help with whatever new retarded military adventurism our politicians are plotting. The reason America invoked Article 5 was to give an air of international legitimacy to the invasion of Afghanistan, and if doing something like that again isn't on the table then maybe American politicians will be slightly less likely to think that a new war will pay off politically.

We're both better off if Europe can comfortably cut America loose. Europe building up their domestic defense capabilities is essential for this and will bring about a greater chance for long term peace.