For one, Philly is the 4th biggest TV market, and Chicago is the 3rd biggest. It's going to have playoff implication in Dallas (5th biggest), possibly NY (1st) (although extremely unlikely), and Detroit (11th)
In comparison, Boston is 7th, and Baltimore is 26th. And don't see any major markets really caring about the game too much. Maybe NY (with the Jets). So from a TV market perspective, it seems like a pretty big no brainer.
I'm not going to complain though. It's always a thousand times louder at Sunday night games than afternoon games. Anyone that would rather play in Baltimore on Sunday night than at a 4:00 game is crazy.