One the rare occasion i have purchased a United BE seat (and assigned middle in the back), I have approached the gate agent and politely asked if there was a better seat available for a Gold million Miler and have generally been accommodated if there was one available. Makes sense to me. The plane is about to board and if they haven't sold the better seat by then, they never will. A little goodwill for the pax and no loss of revenue for UA. And United needs all the goodwill they can muster these days given their atrocious performance over the past few months.