Ken Burns uses the conservative columnist George Will as one of the commentators in his monumental documentary miniseries on the Roosevelts. I suppose he felt he had to include such a conservative commentator lest he be accused of not being "balanced." PBS makes a point of being balanced in this way.
At one point, Will says that Americans had always believed that they had the right to the pursuit of happiness, and that government should protect that right, as it says in the Declaration of Independence. But, says Will, FDR goes beyond that to try to give the people happiness itself, that is, money. He is referring to the New Deal social insurance programs, like Social Security, Unemployment Insurance, Aid to Dependent Children, and so on. Will clearly believes that this goes beyond the Constitution, which he says both Roosevelt presidents treated as just a nuisance.
Will's fundamental error is one commonly made by professional economists. It is the identification of money and happiness. FDR and other liberals do not and did not support social insurance because they think it will make people happy. Most of the involuntarily unemployed, single mothers, ill and disabled people, and others receiving money from the government are not particularly happy about their circumstances. They would rather not qualify for that government check, thank you very much. The point of social insurance is not to make people happy, but to enable people who would otherwise be impoverished to live a life of dignity. It is to enable people to have access to the institutions and services that might help them improve their condition. It is to help pay the rent, put food on the table, pay for the bus fare to get to a job, or to a doctor's office, or to the church.
So happiness is not what this is about. Money doesn't buy happiness. Seeking money in order to be happy is a vain quest. Giving money to the poor thinking you are making them happy is silly. Only economists and children believe these things. Social insurance is there to "promote the general welfare", an object endorsed in the Preamble to the Constitution.