The advantages are huge. Welfare programs as they currently exist give families several small piles of money (LIHEAP, SNAP, TANF, etc.) that each are limited in what they can be used for. Because of that, if for example you live on a commune and you don't need food stamps but you don't have enough money for clothing, the welfare system can't help you.
Far more importantly, if you need the money to buy a decent suit so that you can interview for a job -- or you need the money to go into business with a partner -- or you need the money for a vehicle so that you can get to work -- NONE of the current welfare programs can help you. A basic wage gives each individual complete responsibility for how their money gets spent, which is why it enables people to build better lives for themselves and escape poverty -- which the current system is heavily slanted against, with limitations that encourage people to keep their incomes low in order to maximize their benefits.
So you have less cost to the government, which means greater efficiency and smaller required oversight. You have greater benefit to the people receiving the money, along with more agency held by the people receiving the money (a.k.a. fewer government regulations). In a lot of ways, the basic wage really is the most Libertarian form of social safety net.
The only notable downside is that yes, some people will choose to recuse themselves from the workforce and live entirely off of the basic wage -- but as the experiment proved, the vast majority of those were college students and mothers, both of whom have ample external obligations that we should probably be allowing them to attend to anyway.
