In the first movie, sure, and he hits that nail on the head. But movie Optimus has become his own entity over time.
Movie Prime doesn't like casualties either. Are we forgetting the KSI scene? "They were my friends!"
He obviously cares for his fellow Cybertronians.
"How many more of my kind must be sacrificed?"
He's kind of fed up with Autobots continuously dying for humanity, and the bias towards his own race starts to show. He's more human in that capacity. It's like Americans in the 1960s complaining about being in Vietnam (that's history, it's a fact, it happened, not political!).
Also, Movie Prime probably doesn't want the death of anyone the majority of the time either, but in the '86 movie, Prime says "One shall stand, one shall fall" for a reason. He knows he either has to kill Megatron or be killed trying. Cue Hot Rod. At the end of Dark of the Moon, yeah, it probably would have been more G1ish of Prime to accept Megatron's truce, but, y'know, Michael Bay. Not sure how to defend that one. He was probably fed up with the fighting and just wanted an end to it once and for all. How was he supposed to know that KSI would hook him up and unknowingly turn him back on?
I'm sure a reboot will happen eventually. Transformers has had NINE television shows (and that's just the US ones!) in the past 30 some odd years. I'm sure this current live-action franchise will end at some point and then be rebooted like Batman or Superman or Spider-Man have been for a long, long time. Just not sure if it'll happen anytime soon.
Also, just because it's a reboot doesn't automatically make it good.