You might as well ask In fact, any country in the world with a
     sufficiently large brewer is guilty of brewing beer that is (ahem)
     less than it could be. In an effort to boost profit margins and still
     be acceptable to the broadest possible market, the mega-brewers have
     resorted to using cheaper adjuncts, like corn and rice, instead of
     all barley malt. The resulting less-sweet beer doesn't need as much
     balancing bitterness, so they cut back on hops to save money and to
     make the end-product innocuous to the casual drinker. The change has
     been a gradual one, taking place in small increments over many years,
     so that most consumers would not notice the difference. These
     practices are followed up by huge, multi-media, marketing campaigns
     that attempt to sell brand image rather than beer flavor.

     American brewers take the biggest hit because they're the best at
     this game. In addition, most people outside the U.S. only see the
     brews exported by the mega-brewers and judge the entire market by
     these examples. But such blatant generalities as the opening question
     always fall short of the truth. The truth is that excellent beer is
     also being brewed in America and
     Germany/England/Canada/Mexico/Japan/Holland, etc. and the way to
     enjoy good beer from any country (or avoid bland beer) is to
     patronize the brewers that provide it and avoid the ones that don't.