Great post. It's my favourite Christmas film. I think it's worth remembering the political context.
When it was made in 1946 the US had not that long before had to contend with the Great Depression which President Roosevelt tackled in the 1930s with the New Deal, pumping huge amounts of government money into projects that would create jobs, give welfare support to the poor and turn the economy around.
Then came World War II and when the US entered the war there had to be a lot of government intervention and central control of the economy to ensure that industry focussed on supporting the war effort.
For a country founded on capitalism and libertarianism, these were revolutionary changes. After the war there was a strong reaction to all of that, fuelled by the Cold War and fear of what was going on in the USSR, China and several other parts of the world, where Communists were in control. US Communists had enthusiastically supported the war effort because they were on the same side as Stalin but once the war was over obviously the US and the USSR were effectively at war against each other.
A great many people working in Hollywood had come to the US from Europe and had brought their left-of-centre political views with them. Some were or had been paid up Communists, others were fellow travellers. They were going to suffer very badly in the post-war years when there was a witch hunt against Communists which destroyed many careers. The House Un-American Activities Committee started its hearings looking into Communist infiltration in Hollywood in 1947, the year after It's A Wonderful Life was released.
The director, Frank Capra, was not a Communist, or even close to one. He was born in Italy, brought up a Catholic and voted Republican once in the US. He opposed the New Deal. However, he seems to have been a lot more tolerant of diverse political and social views than many of his fellow Republicans. When It's a Wonderful Life was first released some people thought it was subversive, including the FBI. (Link below to interesting article about the FBI's view of the film.)
The rich man, i.e. a successful capitalist, is the baddie. He cares about nobody but himself and has no redeeming features. Nobody likes or loves him, everybody is afraid of him except the Bailey family. The good guys are the Bailey family, turning their backs on get rich quick schemes and trying to redistribute wealth, support people who are struggling and improve social mobility. Everybody loves and admires them.
(I think that falls down as soon as you think about Harry, who is doing very well in his father-in-law's business. George and the rest of the family are very proud of him. Mr Potter is loathsome not because he is a successful businessman but because of his moral failings. Mind you, there's another way of looking at Harry: https://patch.com/new-jersey/westfield/bp--its-a-wonderful-lifeif-youre-harry-bailey-thoughtbe5cf8386d )
Also, more subtly, the hero is not happy living a quintessential American life in a small town. Apparently the FBI thought attempts to show how suffocating small town life could be were Communist-inspired attempts to undermine US society and values. 
https://www.smithsonianmag.com/smart-news/weird-story-fbi-and-its-wonderful-life-180967587/
Bit of an essay!