Murder doesn't make him evil, especially in an rpg setting. Almost every major character in these kinds of games is a murderer, the protagonist especially so. The Baron isn't a good man, but there's a lot of things in between good and totally evil.
If there is something that makes him evil, it's the way his thugs acted towards the villagers, essentially robbed and raped to their heart's content.
But... from the game he just seems like a Robert Baratheon kind of guy, trying to drown his demons in a drink, doesn't much care for a world gone mad.
Perhaps he just didn't interfere because that was the only way to keep them in line? Yeah, he's not a good guy by any means.
It's not just murder. It's how he takes a life, and why, and what he does for years. It's all things taken together. A bit of crying and charisma doesn't wash it away. As I said repeatedly, he's not evil by RPG standards. But he certainly would be by ours.
I agree, but charisma aside, it was not just a bit of crying, he pays a heavy price, one way or the other.
And I think he starts to realize, the horror of what he had done towards the end. Given time, it is possible that he would have changed, alas...
Wait, Witcher 3 tries to sell this person as being just morally grey? 
No. TW3 doesn't sell anything. You have the option to completely denounce him as a thug, or to be somewhat sympathetic with his situation.
(which is rather brutal, even if it's his fault mostly)