You're right that the excitement is usually greater the first time or two.
Hershey is also simply a better draw, no matter how much the stadium needed work. It looked and felt more like a state championship venue should.
Last year Harrisburg was in the final. It's much closer to CV than either NA or SJP.
IMHOTEP never draws many fans especially on the road. There are understandable circumstances why that's so.
A lot of SJP people went to the IMG game and the first LaSalle game, but they (we) often have a problem with attendance. Not having an actual home field means having to figure out where the game is and how you can get there every week. They played a "home game" against Judge at Conwell Egan, which is very far for nearly everyone in the Prep community. Norristown, where they were the home team in the PCL championship against LaSalle, was much closer to most LaSalle fans than to most SJP fans--and the site was chosen five days before the game. And it's true that the expectation game will be a blowout reduces the incentive.
I know some will say the answer is for the Prep to play a national schedule. But, as I've said on here before, they can't because 1) they don't have the money to be travelling around the country every other week--they make one trip by plane each year, 2) almost all the other teams people want them to play (the North Jersey powers, the teams from FL and GA, the teams from DC, and the teams from CA--even Bishop Gorman from Nevada) very rarely if ever have openings after September because they have league games to play, and 3) they have their own league games to play and as a founding member of the PCL, they are committed to those games. It's also the case that winning the state championship means a lot to the players. People from other parts of the state probably don't realize that people in south Jersey generally identify much more with "the Philly area" than with the state of New Jersey. That goes for just about all of south Jersey. Go down to Ocean City, Avalon, Wildwood, etc. in the summer and you'll find very few from North Jersey and a lot from SE PA. Plus the media market is dominated by Philly.