Ridership is up a lot locally, especially on the suburban commuter lines which ferry people in to city jobs.
Commuter rail lines are fine, and they pull a lot of cars off the highways which is rather important given the relative lack of feasibility of expanding highway access into this city. But they don't do all that much to reduce automobile dependency unless development patterns around stations are changed drastically from what they currently are most places. The goal for transportation and other planners should be to make it possible for more households to not have one car per driving age member.
Since so many people simply accept that automobile ownership is a necessity, they're unlikely to really factor in the cost when they make decisions. They see it as a need, so they pay for it. But a relatively low estimate of the annual cost of automobile ownership is $6000. Generously assuming that if you lack a car you'll spend about half of that on transit, taxes, occasional car rental, etc, you're still left with $3000. That gives you an extra $250/month to put into a mortgage.
