What was needed were more intelligent robots able to decide how to do a task, and lead other robots. Early on Robots were only able to perform simple tasks.

The classic Megaman series came before the X series. Mega Man X and the Reploids based on his design have total free will on par with a human. To put it simply, Mega Man and the Robot Masters of his era are bound by the three rules and their programming. This means they have full-free will and could choose to harm humans if they wanted to. Light to ensure he was not a danger to humans, Reploids based on X's design were not put through testing. While X was put through 30 years of tests by Dr. This is where the danger of Reploids come in. The danger of course is that without the three rules of robotics, X could hurt humans if he chose to do so. He is able to make the same choices a human could. Unlike Mega Man and the Robot Masters, he is not bound by pre-programmed laws or programming. Mega Man X has full free will that is on the level of a human.

If they are attacking humans it's because they were programmed to do so. Not only are they bound by their programming, but they can't break the three rules.

Mega Man is bound by the three rules of robotics which means him and other Robot Masters can have personalities and emotions, but they don't have free will.

Megaman x height