From Glenn Greenwald, of The Intercept:
While there is certainly truth in the claim that Trump’s use of the suffering of soldiers and their families is politically opportunistic, even exploitative, this tactic is hardly one Trump pioneered. In fact, it is completely standard for U.S. presidents. Though Trump’s attackers did not mention it, Obama often included tales of the sacrifice, death, and suffering of soliders in his political speeches — including when he devoted four highly emotional minutes in his 2014 State of the Union address to narrating the story of, and paying emotional tribute to, Sgt. Cory Remsburg, who was severely wounded by a roadside bomb in Afghanistan.
George W. Bush also hauled soldiers wounded in his wars before cameras during his speeches, such as his 2007 State of the Union address, where he paid tribute to Sgt. Tommy Rieman, wounded in Iraq.
There are reasons presidents routinely use the suffering and deaths of U.S soldiers and their families as political props. The way in which these emotions are exploited powerfully highlights important aspects of war propaganda generally, and specifically how the endless, 15-year-old war on terror is sustained.
. . .
By dramatizing the deaths of Americans while disappearing the country’s victims, this technique ensures that Americans perpetually regard themselves as victims of horrific, savage, tragic violence but never the perpetrators of it. That, in turn, is what keeps Americans supporting endless war: These savages keep killing us, so we have no choice but to fight them.
Greenwald points out that our natural sympathy for family members of brave dead soldiers is consciously reverse engineered at events such as President Trump's recent speech, such that the heroism of the soldier appears to make the war a worthy war and the President a worthy President.