Unforgiven:
In my opinion, the movie is about people taking the law into their own hands when the justice system doesn't work for them.
Little Bill (Gene Hackman) has a reputation as an effective law officer and the movie paints the perspective of him being cold and unflinching in his judgements. But you have to keep in mind that if you consider the lawlessness of the time and the fact that the justice system, by its very nature, was to some degree arbitrated by the authority figures in each town, it's hard to be able to easily judge what is an acceptable punishment and what is not.
Little Bill determines that the appropriate punishment for 'cutting a whore's face' is taking away some of their horses. His rationale for a punishment that some have called lenient is that the boys 'weren't given to wickedness in a regular way.' The madame of the house (forget her name now) determines that the punishment wasn't good enough and that she wants her blood, even if the victim of the crime eventually comes to accept what happened (evident in her mannerisms when she talks with Will Munny later in the movie.)
So the thought provoking aspect of this scenario comes from whether or not the punishment is just based on the justice system at the time. For me, it's not an easy question to ask and it's impossible to judge by present standards.
There are other quandaries that are not so easily solved just at a casual observation:
Is Will right to take the job? Is Ned right to leave his wife? Should either of these men be accepting an illegal bounty job, given their present responsibilities? They both struggle with the choice and they both make great sacrifices for it. The pros and cons of their decision to go out on the road again are thought provoking.
Little Bill's method of law enforcement is also worth thinking about. Ruthless and cruel or necessary for the lawless times when armed men will ride across the land, circumventing the law wherever they think they can? What about when they come to his town KNOWING that a prostitute is offering a bounty on a couple of cowboys when the judgement has already been passed and the punishment rendered by the justice systemof the time and region? Is Little Bill wrong to beat the shit out of every piece of garbage bounty hunter that comes to his town trying to break laws and damaging his authority over the town? If he lets those people come there and do those things, isn't he just another lame duck tin horn sherrif that doesn't believe in the badge he's wearing? He says he's done work in some nasty places and he's seen how a lack of order can contribute to the complete downfall of society and he's doing his best to make sure that doesn't come to the town he's responsible for. Or is he just a ruthless prick? It's not an easy call to make if you look at it honestly.
What about The Scofield Kid? Is Will encouraging his dangerous daydreaming about glory, a la Billy the kid, by riding with him? Should he be?
When Will kills all those people for upholding the law...should he have done that? Ned was publicly displayed to set an example for any other bounty killers that came by Big Whiskey, a fate that he could have avoided had he simply talked (which Little Bill afforded him, and you can't argue that he would have killed Ned anyway....there's no way anyone can say that with any conviction because Little Bill was never shown to be a liar at any point in that movie.) One could argue that he was also black, which played into it, but I personally don't buy that: it was common to let convicted criminals hang publicly to set examples back then, regardless of skin color. That he was 'black', and he married an 'indian', probably only made him a further outcast in that day and age. But that's the key phrase: that day and age. Will didn't kill those deputies in the end because of some righteous cause to clean out any corrupt justice system. Hell, he's probably so used to what he feels is an unfair legal system that it doesn't even phase him. He killed them because they murdered his friend, so he got piss drunk and wiped them all out. It was a crime of passion, plain and simple. Revenge. But was what he did a just thing? Was it right? Was Will above the law at that point in the movie? Or, by reverting to the evil man he used to be in his youth, did he justify the attitude and law practices of men like Little Bill, who'd seen Will Munny's type before and decided that there was only one way to keep such hardcore criminals in line.
I think the fact that I could write this much, and a whole lot more, about this movie shows how much it made me think. In my opinion, Unforgiven deserves every accolade it's ever received and more.
As for Million Dollar Baby, for the sake of brevity since I've already written way enough about Unforgiven, I'll just say that the fighter-mentor dynamic is explored with enough detail and honesty that their relationship, and the consequences of their chosen path in life, led me to consider everything that it took for them to achieve what they did and for the decisions made, by both of them, at the end of the film.
I hope this answered your question, whether you agree or disagree.