Ford Field actually sounds alright. I wouldnt mind sitting in a Mustang section seating. Minute Maid Park and Tropicana Field are lame. Why not Kool-Aid Arena and Sunny Delight Stadium?
Of the corporate named football stadiums in the NFL, Reliant may be the best. Maybe because it's not too overt, it could have easily been Reliant Energy Stadium which would've been much worse. It's better than University of Phoenix Stadium or Bank of America Stadium or Gillette Stadium.
At least its not the jazzhole "energy solutions arena" I'm sure they love being named after a company that dumps nuclear waste.
Answer to the thread title question: No. NRG owns Reliant Energy Retail and acquired the naming rights during their acquisition in March of 2009. Per SEC filing: "As a result of the acquisition of Reliant Energy, the Company acquired the naming rights, including advertising and other benefits, for a football stadium and other convention and entertainment facilities included in the stadium complex in Houston, Texas. Pursuant to this agreement, the Company is required to pay $10 million per year through 2031." Link