There’s been a curse of sorts on the Terminator movies ever since the second one ended, though it’s hard to know if anyone can really explain it. One thing is certain though, no one person has ever returned, barring Edward Furlong of course, to the role of John Connor. And to be fair, Furlong only came back for one sequence in which he had to be reverted back to his younger self so that the continuity could be kept for another trek into the future where the Terminator movies have been having such a difficult time. Bale simply had no interest in coming back, though whether it was because Salvation received such horrible reviews or because the fan base didn’t want to stand behind it is hard to tell. Personally I enjoyed Salvation more than Dark Fate or Genisys, largely because it was so much grittier and rooted in the type of future that the original movie indicated was bound to come. Dark Fate was of course looked at as an abysmal failure and largely touted as a movie whose main goal was to state that ‘the future is female’ even while bringing back a popular male character that helped to save the day despite the badass females that were supposedly tough enough on their own. Genisys was kind of a cosmic joke on the whole Terminator franchise really as it seriously retconned the story of Kyle Reese and the connection he had with John Connor, while at the same shaking the timeline up in a way that might have left a lot of people dizzy. Michael Kennedy from Screenrant might actually agree with that assessment.
To be realistic every movie following Judgment Day has been an epic blunder that was used to try and push a narrative that was somehow encapsulated perfectly within the first two movies. Even without going into the future for a prolonged period of time, the first two movies managed to give a sense of urgency that felt real enough to really hammer home the point that humanity had orchestrated its own downfall with the creation of Skynet. In Rise of the Machines it simply felt as though the audience was being led politely by the hand and being told to pay attention while John Connor and his future wife were a forcefully acquainted and apprised of the situation, that she had sent the terminator back in time to save them. Katherine Brewster kind of became a more centralized character at that point, and yes, the female terminator was a definite shift in the way of things, but with the onset of Salvation things went back to what people might have expected, which makes the fact that Salvation was so heavily criticized kind of confusing. Apparently it was enough for Bale though, since he decided he wouldn’t be coming back, ever.
It didn’t help that the rights to the movie bounced about from one company to another before they were finally settled into the lap of someone that wanted to move forward. Of course, learning nothing from the mess that had been created with Salvation, someone went and attempted to create another movie, coming up with another look at how the timeline could be messed with and possibly destroyed in a way to make it appear as though Skynet was tossing everything but the kitchen sink at the humans. With each movie the terminator’s became deadlier, more advanced, and definitely more capable of withstanding any damage that their predecessors could dish out. With Dark Fate, the metaphorical middle finger that was aimed at the third through fifth movies by James Cameron, the attempt was made to redo the whole thing and send it off in a different direction. People were actually excited to think that Edward Furlong would be involved, right up until his character took a shotgun blast to the chest, eliminating the role of John Connor with little to no fanfare, something that really pissed a lot of fans off from the get.
The death of John Connor was bad enough, but in his place we were given a human/machine hybrid that had a seriously bad attitude and was a poster child for third-wave feminism in a lot of different ways. On top of that, even with Sarah Connor coming back into the picture the laughable truth was that without Arnold Schwarzenegger’s return that the new and improved terminator would have been the end of the three women that were supposed to save the world. Take from that what you will, but the removal of John Connor appears to have put a serious dent in the story that wasn’t bound to be fixed so easily. It’s probably best that Bale got out when he did, as his reputation didn’t take too heavy of a hit from this movie.