It's very rare for a program to provide valuable redemption options outside of their business. That's where it becomes "real" money. Taking up another parking spot costs them nearly nothing. Buying airline points to give to you has a real cost.
I've actually found PS to be a good value in terms of $ saved vs. $ spent, even when compared with cheaper parking options for personal trips. But if you have very low- or no-cost alternatives then yes, it's a poor value.
I haven't found any other options at PIT to earn points, let alone those to redeem elsewhere.