I find it interesting that you see 'save thousands of hours of human labor' as something that's surely positive. What should those people start doing instead? They also need an income to get bread on the table.
Whatever makes them happy, petting their dog, having a conversation with their friends/family, make some music that one person listens to, literally anything produces more value for society than performing arbitrary unnecessary labor which could be automated for near-zero marginal cost.
We should divert that capital to something more productive, tax the process and kick them back a basic income to do whatever they want with. If what they really want to do is what they currently do at their job, whatever, they can keep doing it while supporting themselves on the basic income, but that'd be their uncoerced choice.
Most people are unhappy at work and only go because they are required to to survive. If our society weren't so myopic and steeped in puritan ethics this would be as absurd as asking whether the thirteenth amendment was going to be surely positive.
Between pointless distraction and work, most people will pick the latter, especially after a solid decompression period, in spite of the surface enjoyability balance favoring the former.
Being paid is not a substitute for enjoying the fruits of one's labour.
On organizing work. Chances are that at some point you'll want to work on things beyond the scope of what you can accomplish on your own. Or want to have a larger impact on the world / other people's lives. The big question is how to organize the work of people at society level. The pay per work model has proven to be very effective and gave us the marvels of the modern world.
On the shadow side, the pay per work model has become heavily geared towards exploitation, as in exploration vs. exploitation. We are at a point where worker conditions in a BigTech warehouse, or as a mechanicized Turk, are meticulously quantified exploitation. At the same time, we find it natural to expend the energy budget of a small city to enable machines do large-scale exploration.
On one hand technically it is better than nothing immediately for those in need and is fraud resistant in that it consumes time and any better paying job without major negative externalities would be a better use of their time.
The negative is that it does nothing productive and those who are dependent on it aren't able to use their time productively on anything else.
While the problem of lack of income and lack of good uses for their labor certainly should be addressed just because it provides income doesn't make it a good thing overall.
It is one of those things which puts the "dismal" in the "dismal science" term for economics - regardless of any misgivings over calling it a science. It is essentially a subset of human organizational and incentive problems which the economy "is designed" (technically more emergant even if it is literally a planned economy) to solve.
http://www.zpub.com/notes/idle.html
People won't stop finding things to do, they'll just get to choose things further removed from survival.
If X becomes cheaper, humans spend the surplus resources on Y. If Y becomes cheaper, humans spend the surplus resources on Z. And on it goes.
"Save thousands of hours of human labor" doesn't mean humanity is working thousands of hours less total; it means that they accomplished the same specific X with thousands fewer hours (and then almost certainly spend thousands of hours on Y).
That's not just an armchair theory. Time-honored tradition of technology advancement. Agriculture fell from 70% to 25% of all U.S. jobs in a single lifetime. Staggering economic change. And humanity is better off for it.