I'd like to think we have become comfortable with the taste of tannin because it's an essential component of most good red wines. Along with acidity, tannin provides backbone and structure, as well as helping a wine to age. Too much tannin can be unpleasant, but provided the dryness is balanced by other things, it's part of what distinguishes red wine from fruit juice.
But have we really moved on from sweet reds? I'm not so sure. The majority of the UK's most popular red wines contain noticeable levels of residual sugar. I'm not talking about the smoothness that comes from higher alcohol levels here - remember that alcohol is fermented sugar - but from actual sweetness. Winemakers leave unfermented sugar in their wines because they know that sweetness sells.
The leading Australian brands realised this a long time ago. Indeed, sweetness is one reason why mass-market wines from Down Under have been so successful, claiming six of the top 10 brands in the UK. If anything, the top American brands are even more sugary - you should try a bottle of Blossom Hill.