This is essentially Paul Berman's thesis of "Terror and Liberalism," that the war we are fighting today is the terrible thing that got started 80 years ago in Europe and has never come to an end.
I agree with the sentiment that a "mature liberal impulse" exists. I saw a lot of it while working on the Arnold campaign. The sentiment includes a great deal of anger and frustration with the actions of both parties, yet does not seek to isolate itself in rage. It wants to engage.
I also agree with the characterization of the enemy in this war. However, remember what was required to bring us out of our historical isolation in the first place -- two world wars.
Sadly, I think that the only thing that woul mobilize any popular sentiment along the lines you suggest will be more deadly terror attacks here, or on our close allies.