The alternative is like feeding an animal instead of letting it live the lifestyle it's adapted for. That helps it in the moment but over time its capacities atrophy and it ends up weakened, twisted and harmed with nothing to spend its natural instincts on.
The "job" can be things like volunteering, artwork, finding a cause, inventing, raising children, teaching...
Work can be subsidized and based around personal interest and achieve the "psychologically healthy" aspect that you describe.
When they used to say that you'd make more money going to university, that is what they were talking about. The idea was that if you went into the research labs you'd develop capital to multiply human output, which is how you make more money. Most ended up confusing the messaging with "go to university to get a job — the same job you would have done anyway..." and incomes have held stagnant as a result. It was an interesting dream, though.
But not really what everyday normal people want. They like to have somewhere they can show up to and be told what to do, so to speak.
Sure, I guess -- if you're not charging for your time, it's more efficient to use human labor than AI+robots.
> inventing
If we get working AI, humans will be unemployable at inventing useful things.
> teaching
There are already multiple startups trying to replace teachers in the classroom.
The point you're responding to is that humans would be able to do it for personal fulfillment and thus preserve their mental health, not to be useful to someone else.
The ideal society is one where humans only do things that they actually enjoy doing, whatever that is, and automation does the rest. Any human being forced to perform labor not because they want to, but because they need to do so to survive, should be considered a blight on the honor of our species.