Oh, yeah, there's no question that a lot of the world was willing to let the U.S. shoulder the burden. But then, post-Soviet collapse for a decade or so, the world was basically America + Others as far as military significance went. Not to mention that a large part of the reason why we have this sort of military spending and other western democracies don't is because they're spending it on social programs instead.
But then, people like to try to portray it as Europe et al. profiting from American expenditures and nothing else, which is false. They also depend heavily on the U.S. to prop them up should serious conflicts arise--their national sovereignty to a certain degree is in U.S. hands, insofar as that if we pulled out when confronted with a meaningful foe they'd be SOL. See: the Cold War and what would probably have happened to yurokin if we'd gone full isolationist again. Not much of a worry in the '90s, but now? A strong standing military isn't a pure good any more than strong social programs are (see: the influx of wealthy and middle-class "refugees" looking to leech off of Yurobenefits of late--the real refugees are mostly going to... anywhere in the region that'll take them, really), but it's a damned nice thing to have when authoritarianism is on the rise. Or not, if that trend is internal.
So on and so forth. People who genuinely believe that issues like this are monodimensional are bonkers. Likewise, Trump's bonkers. Trumpian isolationism won't cause v2 of the issues that arose from it last time, but it won't be a good thing either.