Knowing how the PA operates, I'm sure this is a case of go along to get along, that is, getting the same radio system that "everyone else has" in NJ. But, then again, don't be surprised if the PA does come up with their own P25, but not on the statewide system.
They always try to "improve" things, but tend to leave a thing or two out of the "improvement," leaving those who have to use the new and improved system baffled (no matter what it is) why they didn't do it right.