>Once he popped Cesar though, it was clear: this was all a
>power grab and nothing more.

Koba wanted what he thought was best for their species. he would've been happy to remain a lieutenant had Caesar attacked the humans, but after giving his leader three chances (first contact, letting them reconnect power, then seeing one of them pull a gun on an infant ape), the only way left was assume leadership of the group.

Caesar had the same motives in the first movie: he saw a better life than what the apes had in captivity, took out their leader and made it happen. he also knows he'll be tested anytime the tribe questions his leadership or strength. "apes look for the strongest branch." to that end, how Koba did Ash was cold, but understandable -- Caesar had incredible loyalty and acts of dissent could be fatal to him quickly.

finally, Koba was right about *a lot* of things. once the human colony had power and radio contact back, I don't think it'd take long for them to look at the remains of the Golden Gate Bridge and think, "we've got to take out these apes before they overrun the entire state and nation." Koba died a traitor but may have saved his species in the long run.