I think PHLapproach called it right. They were worried, and rightly so, about the traffic on the parkway interfering with the signal. Even for a normal doppler VOR, the cleared area around the facility has to be of a significant size. You can have obstructions, and most of the time it will be OK
, but it's hard to predict beforehand just which obstructions can be safely tolerated. A couple of freight containers in the vicinity can
muck up the signal. Now, imagine a traffic jam on the parkway full or trailers loaded with who knows what?
Also aesthetics, obviously.
Check this place out in Google Earth, while you're at it: 35° 23.353' N 97° 37.458' W.
I thought I was doing good trying to avoid those airport hotels... and look at me now.