I've been thinking about this a lot. Another reason why the other films are so poor as well, not only because of the story, but also because they lack another element that helped make the first two great. Something also missing from other movies with paranoia and chase scenes, which the first two Terminator movies delivered in spades. A THRILLING and CHILLING score.
Brad Fiedel is to Terminator what John Williams is to Star Wars and Superman and Raiders. He helped bring an intense and weird mechanical, constant beat to these movies. There's simply no real energy or life to the other two soundtracks. What he added was raw power and drive.
Another thing I've found boring about many of the sequels is that John Connor is painted as this flawless savior of all mankind... he's just perfect and so important and not capable of making mistakes. Anyone knowing human nature would quickly acknowledge that if you are brought up to believe you'll be this and that, that you'll eventually try to rebel from it and those trying to push you in a certain direction, so you can shape your own future and yourself the way you want to be and not how others see you or try to force you into becoming. Where's the rebellion? Where's the poor choices? Where are the mistakes that could end up getting others killed because you either act superior to everyone because of what you're told you'll become or because you are trying to rebel from it? Where's the growth? Where's the drama? Where is the boy, who turns into a man, who witnesses the horrors and knowing he really can't stop it... and... still trying to help turn things around. I want the reluctant hero, not the perfect, flawless pedestal hero, who's as realistic as a cardboard cut-out.
Like Morpheus said to Neo: "There's a difference between knowing the path and walking the path". And THAT is what Connor meant with the message he gave to Reese to tell Sarah, that, we are masters of our own fate. NOT that the future can be changed.
