I've also wondered about the hatred of American lagers, they're basically just German pilsners.
What do you mean by "American Lagers"?
If you mean the big brand stuff like Anheuser Bush, Miller and Coors, I would have to strenuously disagree.
These American brands really have made their product as flavorless as they can. Their big advertising push is often things like "no aftertaste".
Once upon a time--before prohibition--these brands DID produce beers similar to Bohemian lagers. Both Budweiser and Michelob take their names from Bohemian towns that inspired each brew. The recipes have been altered several times to make them less and less flavorful.
Some EXCELLENT American lagers: Brooklyn Lager (a vienna style), Brooklyn Pilsner, Sierra Nevada Summer Fest (awesome Helles/Pilsner), Troegs Sunshine Pils, LaGunitas Pils.