The argument from evil presumes a standard of comparison. A better possible world, a better feasible alternative, is the foil in contrast to the real world.
Years ago I saw The Final Countdown. It's an alternate history film in which a nuclear aircraft carrier passes through a temporal wormhole and returns to the day before the Pearl Harbor attack.
Once the captain figures out what's happened, he's been given an opportunity to change history. He has advance knowledge of what will happen, absent intervention, and he has advanced military technology to shift the balance of power.
So the film has a great dramatic premise. Unfortunately, the director lacked the interest and imagination to exploit that premise. But it's a useful illustration. Of course, the film raises the usual time-travel antinomies, but as a thought-experiment, we can bracket that.
What should the captain do? Should he take advantage of the situation to avert the Pearl Harbor attack?
There are different ways of developing the film's dramatic premise. The carrier has only so much jet fuel and ordnance. After thwarting the Pearl Harbor attack, should he and the crew focus on the Pacific theater or the European theater? Should he destroy the Japanese navy? Or should he steam off to Europe and attack German assets?
Or what about selective interventions? Do something now, then lay low for a few years before using the carrier to disrupt the Soviet nuclear program?
Should he simply prevent the Pearl Harbor attack, then sink the carrier, while he and his crew melt into the 1940s–with no one the wiser?
The question a film like this raises is, after having done whatever they do to improve the immediate situation, they pass back through the temporal wormhole to the same date in the present, before they were transported into the past, what future awaits them? What will the altered future look like? They won't be returning to the same world from whence they came, that's for sure.
The Pearl Harbor attack gave FDR the pretext he was spoiling for to get both feet on the ground in the war effort. In the attack itself, 2,335 U.S. servicemen were killed and 1,143 were wounded. In addition, WWII resulted in 1,076,245 U.S. servicemen dead and wounded, as well as 30,314 MIAs. So there's an obvious sense in which preempting the attack would be better for those who were directly or indirectly killed or maimed as a result of the attack, not to mention their bereaved or bereft family members.
LIkewise, Japan would be spared the firebombing of Tokyo as well as the nuking of Hiroshima and Nagasaki. So that would be better for them.
But, of course, there are tradeoffs. Drastic tradeoffs. Dire tradeoffs. Absent the Pearl Harbor attack and the American counterattack and occupation, Japan would remain an aggressive military dictatorship for however long.
England might well fall to the Nazis. That doesn't necessarily mean Hitler would conquer Europe. But there's a difference between winning and losing. The Nazi war machine would be able to do a lot more damage before it ran out of men and materiel. Far more Jews would be exterminated. You might end up with a stalemate between Russia and Germany. Perhaps they'd carve up Europe. Or maybe Russia would overwhelm Germany and take all the marbles. That in turn might give a boost to communism in Latin America.
Consider some of the things that hadn't happened before December 7, 1941. FDR hadn't been reelected to a fourth term. Truman hadn't been picked as his running-mate. Mao hadn't defeated Chiang Kai-shek. The state of Israel hadn't been established. The Manhattan Project was barely under way.
It's very hard to predict what the world would be like had the Pearl Harbor attack been preempted. Certainly better in some ways for many people, especially in the short term. But worse in other ways for many other people in both the short-term and the long-term.