The only 'fight back' moment I had a problem with was the last one when George killed the slaveholder son and even that was more because I don't think the show did a good job of establishing that the slaveholder father had that much affection or much of a relationship with his slaves which I think they needed to do for that to pay off. I think someone said he was supposed to have some affection for Tom, but I don't remember that being established all that well or at all or maybe I wasn't paying close enough attention. I mean he was nicer than his son, not hard to be, but he was also apparently willing to deny them food and then offered them that lame chicken and hog deal for them continuing to work the land. So the idea that he would help them after they killed his son, even in self-defense, even if he didn't like his son all that much and knew what an arse he was didn't really work. Plus it really wasn't a necessarily moment since the real empowering event was them getting to leave of their own free will not getting to kill a white slaveholder.
Whereas the moment with Kunte Kinte worked for me because there were no real witnesses(well except the British soldiers who stumbled upon him after the fact and had their own agenda which he then played on) and the importance of Kunte being someone still very tied to his African roots and being a warrior were treated as very integral to his character and from what I've read they were more likely to fight back so I though the circumstances fit. I also thought Tom Lea was one of the better developed white characters and that the show did a pretty good job of establishing his relationship with Kizzy and Chicken George and Mingo and the kind of man he was and how that played into their relationship with him.
I also agree it wasn't just a case of slaves being passive or going all Django, but something much more in between and complex in terms of resistance and I thought the series also did a great job of showing that not just with the rebellions and the 'killing moments', but also with the moments like slaves repeatedly trying to run away or less obvious things like the songs they sang and how they were used or trying to hold on to traditions or Kizzy learning to read and write despite the severe consequences or putting stuff in people's food or even playing up to their slave owners in the hopes of getting concessions in return.