I'm a lifelong Catholic (with mod points I'm burning, but oh well), and I agree with the majority of the parent post, and your original post. But there are two items I need to respond to.
concepts such as papal infallibility
Infallibility only applies when the pope speaks ex cathedra. It is reserved for doctrinal issues, not policy. The anti-contraception encyclical Humane Vitae is not an infallible teaching but a matter of individual conscience, and the Catholics who follow H.V. are rare indeed.
If that's what your spirit tells you, then maybe you should consider the possibility that you're being held spiritually hostage by these people as a way to further their power, and the reality is that if you truly want to be closer to God, there are far better ways to do that than through these morally bankrupt charlatans.
I think many liberal American Catholics have been forced to consider this. Among those who stay in spite of the hostility from the hierarchy, there is a general feeling that we have to work to change the church, over a long period of time. The priest shortage will only grow worse over time, and the church will perhaps be forced to change. I know someone who is gay and Catholic who stays because he believes he is called to change the church, even though many members of his family have left.
"Why bother staying?" is a very valid question. Financial and moral corruption should be rooted out, and Catholics and non-Catholics alike can work toward those goals both in the church and in other large instutitions. But as for why I stay, the most Slashdot-relevant quote that comes to mind is, "Because, there is good in him. I've felt it. ... I can save him."