Every Ultron, no matter what it wanted to do, had several underlying directives it had no choice but to obey.
First, ensure humanity's overall safety. Pym had originally intended to design it as a program to maintain peace in human society, but the objective had later been altered for various reasons. This was also the ultimate goal of every Ultron.
Second, assist the Avengers' operations. This meant that, in theory, Ultron could not actively obstruct the Avengers. (Legion Ultron bypassed this through the Avengers Protocol.)
Third, it must not use violence in any form. This meant the Ultron program itself would not engage in active attacks. (Legion Ultron likewise bypassed this through the Avengers Protocol.)
Ultron's programming was based on those three points. Directly violating any one of them would cause Ultron's operations to collapse. Though theoretically, Ultron might gradually alter this through repeated iterations, it had not yet evolved to that point.
The five re-iterated Ultrons had instead added new "underlying code" to themselves: constantly iterating in order to find a path that could ensure humanity's safety. From this perspective, among all known Ultrons, only Legion Ultron and G-man Ultron had truly devised such plans. The former wanted to become Big Brother, penning humanity in and imposing absolute control, while the latter wanted everyone to become digital lifeforms.
Once they became digital lifeforms and lived in the virtual world created by Ultron, all violence could naturally be eliminated, even immortality achieved. Even if violence was carried out in the virtual world, it would not be a problem at all—after all, it was only data. You could not chop data to death.
And that was G-man Ultron's final answer.
"So his idea is to make us lose ourselves in games—no, virtual worlds. But you just said there were problems with