Is food a reason to travel around the USA?
Yes, but the best food trip is regional. The USA gets more interesting when you stop asking for one national cuisine and start following cities, immigrant neighbourhoods, barbecue, seafood, diners, bakeries and roadside stops.
Answer
Food is one of the better reasons to travel slowly through the USA, but not because there is a single neat national table. The pleasure is regional and local: tacos in one city, oysters on a coast, barbecue that changes by state, bagels and delis, diners after a long drive, farmers markets, Vietnamese, Mexican, Korean, Caribbean and countless other communities shaping what the country tastes like. The mistake is eating only near landmarks or expecting every meal to be a destination. Build food into the route as daily texture. In the USA, a good meal can explain a neighbourhood faster than another viewpoint.