What social issue in Death of a Hero by Richard Aldington and All Quiet on the Western Front by Erich Maria Remarque was a concern during WWI and is still present in society today?

One thing you could point to is that both books are critiques of the tendency for Western societies to embrace violence as a positive trait, or as the only way to resolve conflicts. In Death of a Hero, for example, young George is browbeaten into getting a gun license -- the hope is that this "will make a man" out of him. His experience with shooting, however, is horrifying -- he wings a bird, and, in trying to wring its neck, tears its head completely off. This episode is emblematic of George's disgust with bourgeois values, his desire to become a bohemian, and his embrace of "free love." None of these values serve him very well at the front, however, where he becomes a kind of automaton. In All Quiet on the Western Front, it's clear that Paul's teacher Kantorek is urging his students to enlist without fully understanding what the war will be like. Kantorek's betrayal lies in his using his position of authority to advocate for violence. Both books describe, with shocking detail, exactly what the cost of this love of violence is in human terms.
It's also pretty clear that we can trace the origins of the US's current "get tough" rhetoric about immigration or terrorism to the same nationalist ideologies and love of violence condemned in these books.