0.7c per mile is not the best value available in frequent flyer programs. Even with recent devaluations, 6c per mile is possible without too much effort. To earn that high valuation, one needs 100,000 miles or maybe more. For those who earn from one or two trips a year, such a large balance is inconceivable. 1,430 miles is achievable, but award tickets usually start at 12,500 for a domestic one way flight. Rather than save for a few years, infrequent flyers can cash in their miles for a beer at Newark airport. This is a great way for people extract quick value from their flights. Just because it isn't the best value, doesn't mean it's not good value.
At Airport Merchandise Awards
Lufthansa has been doing this for years with their WorldShop in Frankfurt Airport. They have good selection in store and let you order online for in store pickup. They'll also let you pay with a mix of miles and Euros. United isn't close to Lufthansa, but it's a start.