Although I agree with you, Americans vastly prefer dark roasts over light roasts. Mass-market coffee brands have been using dark roasts to mask cheap beans and facilitate consistency over quality (since dark roasting tends to eliminate any personality of the beans themselves).

Having said that, as someone that roasts his own coffee then takes his brew up on flights, I can testify the subtle flavors that make light roasts shine on the ground also don't hold up well at altitude because of our physiology changes at altitude. If United used a lighter roast, I'm sure that many would complain that it is bland and watery.

This is a step in the right direction ... I hope they eventually bring back the espresso machines as well.