A lot to process there and I will continue to think about it, but my first blush answer is this:
We already lack accountability as a society and in my experience it's sometimes the most religious among us that are the biggest dicks to their fellow man. If you think that in general people hold themselves accountable, go into a public restroom or look at the trash "we" leave in almost every public place.
And I am not arguing that we should teach that free will is an illusion necessarily, I think it's an interesting concept to explore philosophically and with a proper understanding, it leads to empathy and altruism. Whether we have free will or not we definitely have emotions and on some level we have a choice how to feel about people and events. The key to happiness, IMO, is to allow yourself to experience life without judgement. This is what I mean when I talk of being present or being authentic. Oinker, below, is upset about a whole bunch of things that he has no control over. I accept that I cannot change those things, I cannot change other people and in fact I believe that it's possible that they can't change themselves. This realization is a part of my path and your disagreement is a part of yours.
I think that if people could choose anything, they would choose to be good because being good feels good. There may be some temporary satisfaction in lying, cheating, stealing or killing, but you can't lie to yourself. If you steal from me you will pay for it and the punishment will come from within. This is the religious concept of conscience.
So then that leads us to consider, why do bad things happen to good people. Who designs a predetermined situation where people experience intense pain and what is the purpose. Well, one explanation is from the book I mentioned, your soul must experience life, both the good and the bad to gain wisdom and gaining wisdom makes you more godlike or more master-like. When you've learned all lessons you will be relieved of your burden to keep coming back to this place with all of these god-forsaken people. My main argument is to enjoy the ride, because even if your sitting in the driver's seat, you're not driving. And if I am right, you'll eventually come to this realization on your own, but not because I told you. Telling you is all about me.