Indeed, I think Rome, Greece and other conquering powers get more respect than they deserve. There's no actual reason so many people have to die for these countries' national ambitions. Feel free to generalize to the US, etc.

Didn't Rome save a lot of lives by pax romana? Perhaps it was actually better in terms of loss of life to be conquered by Rome than have endless wars among yourselves. Applies to the US too.

You can defend a lot of atrocities by arguing "for the greater good" and comparing to uchronic hypotheticals. I could as well argue that without Rome, the greek democracies would have been much more prevalent, and lead to modern democracies much sooner. Or that a world leader would have emerged, leading the ancient world to endless peace and prosperity.

The conquest of Gaul was essentially genocide. Ceaser killed one third of the population, enslaved another, and left the rest to live under Roman rule. My suspicion is Gauls would have been better off having petty wars among themselves than this.