I agree with another poster that your premise is flawed. Aside from the demographic problems with your argument, I find WOGL's playlist and presentation to be far from generic. Generic oldies, for me, would be Oldies Radio, which some small market stations carry. WOGL plays stuff that you'd rarely hear on WCBS, may it rest in peace. It plays a lot of the Philly Sound and it has a killer weekend line-up from Pantano's dance party to Holiday's "Street Corner Sunday" to even Ron Cade's Elvis show. Those shows are appointment listening for a lot of people. I can remember when I was much younger listening to Holiday's show in the back of my parents' car on our way home from the shore on Sunday nights. It was a ritual. WOGL has variety, which is lacking at a lot of oldies stations. WCBS, for example, was always disco-heavy, which made a lot of people hit the scan button.
I would also note that WOGL has some of the best on-air talent around. Holiday's tops in my book and has been there forever, and if there's one thing Philadelphia as a media market has shown, it's that it likes consistency. (This is one reason Action News has dominated on the TV side.) Big Ron's pretty darn good, too, and the other players are all pleasant to listen to. As another poster said, WOGL has out-marketed many other stations and when you add that brand name to the quality, the station has etched itself into the soundtrack of the region. When I go to my local deli, 'OGL's on. My mechanic plays it. My mother plays it. And I, who am far younger than the average oldies listener, listen to it whenever I am in range. It's one of those neat things about Philly-- when we like something, we cling tightly to it.