The fact is we waste a lot of human capital. People claim to be unable to find work, yet it costs $50-80 to have your house cleaned in NYC. The unemployed are simply unwilling to clean houses for $10/hour. According to many on the left, we need more unskilled immigration since immigrants "do jobs that Americans just won't do" [1].
But I do agree that we should eliminate the current ragbag of welfare programs and replace it with a single simple one. So rather than a basic income, I propose a Basic Job Guarantee. The government will give anyone who asks a job at minimum wage. If that is insufficient to pay rent, the government can also provide cheap housing out in the boondocks [2] and buses to the location of the Basic Job.
This is the FDR plan and it worked well. Rather than paying people to watch TV we paid people to build national parks. A basic income without work makes sense after technology makes human labor obsolete, but we are nowhere near that point yet.
[1] I'm not opposed to immigration, I'm simply pointing out that people across the political spectrum agree that many Americans are unemployed by choice.
[2] I.e., move the housing projects to south jersey, don't stick them in midtown manhattan.