I totally support something like this, and believe in the future, a basic income system will be inevitable in most modern societies. The current welfare systems are too complex, shaped by special interests, people exploiting loopholes, or gaming the system for benefit. There is too much abuse, wastage and a large chunk of the population feels a sense of resentment.
Shift to a basic income for all, and you now have a level playing field. It is more efficient, it is harder (or impossible?) to abuse, and no one can argue that laziness or poor health decisions or poor financial decisions are being rewarded. All, from CEOs to Rockstars to unemployed alcoholics are being given a basic income.
The two downsides to something like this :
1) It will be much harder to find individuals willing to do certain categories of high risk or menial labor. You would end up having to pay a LOT more.
2) Inflation for certain goods and services could eat away any gains that a system like this could bring. It is similar to how lowering interest rates does not increase house affordability or put more people in homes, instead it just causes house prices to go up and affordability to remain the same.