Human nature has changed since Roman times. They were surrounded by human death from disease and injury. There was a lot more suffering in life too. No pain killers. Many people would have been crippled by injuries or surviving disease. Killing including suicide was done without much respect for human life. We are not perfect but we are, I believe, improving.
On the other hand, when it comes to war, they did understand peace through strength and that peace comes after total victory. In most cases, only after destroying your enemy without mercy can peace and nation building successfully begin.
Offering a divergent view here,
Roman medicine was more advanced than anything the world would see again until the late
islamic period, and in western europe, not until the very end of the renaissance.
Romans could expect to survive many ailments that would kill you in the
medieval world, and they didn't do stupid things like bleed evil humors our of already weakened people. There were also far fewer communicable diseases like tuberculosis and syphilis in the ancient world - the few diseases that did run along
roman roads, like the
aurelian plague, were devastating and noteworthy for being the exception.
The closer you liver to the frontier, the more precarious life was. Live close enough, and you might fall victim to barbarian raids or lack of access to the best medical care found in larger towns and cities. Much like today, for many people in the world.
I think the
Romans lived pragmatically in that their economy was built on conquering lands to plunder for gold and silver to pay ever-more expensive
military costs. It was a delicate balance between new loot and defending what you
had in terms of territory, taxable population, resources, etc. Outside the
Roman border, much of the world was
still tribal and the tribes largely
had violent tendencies after millenia of fighting with their neighboring warlords, clan leaders and kings over things like their gods, access to women, the best hunting grounds, or perceived insult. For
Rome to civilize these areas, they
had to stamp it out radically, and often enslave the trouble makers - another commodity upon which the empire's economy was dependent.
Ultimately, I think citizens and freedmen understood their prosperity was tied to the strength of the public administration and the legions. Social justice is a luxury today only for those with secure borders and pacifist neighbors. The
Romans had neither, and they knew it all too well.