I'll take your point that this is not entirely a literary debate; it's also a debate over aesthetics and selling out. And I agree that some readers would have looked beyond the logo if Franzen had asked them to. But others wouldn't have: He was already getting heckled at readings by fans who were horrified by said logo. And my guess is that Franzen cares far more about those hoity-toity readers than he cares about the great TV-watching unwashed.
But maybe I think that because I disagree with you that The Corrections is an unsnobby book. I think it's quite focused on snobbery, especially with regards to Enid. Franzen hits us over the head with Enid's bad taste over and over again—I recall in particular one scene that details Enid's selection of utterly tacky gifts for her grandchildren. And snobbery is at the heart of the conflict between Enid and her daughter Denise. When Enid glowingly recounts to her hipster-chef daughter the 18-inch-tall desserts that were served at a Midwestern party, the reader, like Denise, is supposed to understand that Enid's rapture is entirely provincial. I'd say Franzen condescends to Enid for almost the entire book. Yes, he redeems her at the end, but only after exposing everything from her brand of coffee to the berth class she selects on a cruise ship as low-class. I think it's a mistake to translate the sympathy one feels for Enid as a reader to a lack of snobbery on the part of the author.
This is not to say Franzen has no sympathy for Enid, or that he's not conflicted about snobbery. Quite the opposite. But when someone as conflicted as he is gets thrown something like this—the selection for Oprah's Book Club was probably more of a shock to him than to anyone else—you have to give him some credit for not immediately jumping at the money. He was putting his own ideas of literary integrity over what would have amounted to a huge wad of cash. Which is worthy of a certain measure of respect.