How can Bruce Springsteen not yet be on this list? There’s already plenty of stuff here that’s older than 25 years, but all of Bruce’s albums since "The Ghost of Tom Joad" (1995, so 27 years ago) hit both targets: great American music, and great social and political commentary. This list includes "The RIsing" (2002, about urban decline); "Devils and Dust" (2005, about wars in the middle east); "The Seeger Sessions" (2007; self-evidently relevant); "Wrecking Ball" ("2012); "High Hopes" (2014, with important musical contributions from Tom Morello, including "American Skin," about the Diallo shooting); "Western Stars" (2019); and my favorite, "Letter to You" (2020), which I think is one of the E Street Band’s best albums ever, and certainly the best recorded. Including "The Ghost of Tom Joad", as moving a document of American struggle as the Nobel-winning novel it takes its inspiration and title from, there’s ten albums here! But if you extend the dates back to the era of many of the American artists already suggested above, Bruce’s classics from the 1970s are surely among the most important American music ever written.
By the way, my wife is from Europe, I’m a scholar of German intellectual culture, we travel to Europe every year and have many friends there. I don’t know where the OP’s friend is coming from (he doesn’t say), but I can tell you that Bruce is the most well-regarded American musician of them all in Europe.
For good measure, let me also add Kendrick Lamar's "Damn." Few on this list seem to tolerate Hip Hop (and I include myself in that group), but this album is something special, and articulates a perspective on recent American culture in a way that none of the other suggestions here do. That's why it won a Pulitzer.