I do not consider it socialism, even though it is not entirely conservative (and I consider socialism just a euphemism for communism).
Frank Capra was certainly a leftist, and John Wayne refused to be in one of his movies for that reason: Wayne loathed the man.
In a lot of ways, IAWL is a Depression-era picture, like so many of Capra's other films. If people thought capitalism was all about "Old Man Potter," the Rockefellers, Mellons, and du Ponts, they would have overthrown it in the 1930s. We needed attractive figures, like Bailey, who came from the people and worked for the "little guy," to keep the free enterprise system going (even though housing finance and government interventions in it turned out to be the root of many troubles in our economy later on).