For the most part, wagons fell out of fashion in the U.S. mainly due to their replacement by SUVs & crossovers. They way the American market sees it, 'why not sit up higher as an added perk to having all this space to haul stuff?'. Even Honda & Toyota gave up producing wagons in favor of cashing in on the crossover craze, since they sit up higher and afford women the ability to run over curbs, bicycles, etc. without doing any damage. Why produce a Camry Wagon when the Highlander fills the space just as well? I think at one point, the Magnum was the only U.S. wagon available...and you see how that ended. Hello, Durango II.
There's just different tastes in cars here, which also explains why we didn't get the 3-door Fiesta. I'm personally not a wagon fan, but that may be because I was born in an era where wagons were completely uncool, and they remained uncool through much of my young life. When I hear 'wagon', my mind goes directly to the fake-wood-adorned Ford LTD Country Squire. Thankfully the days of exterior fake wood are gone, but perhaps the bitter memories linger on.