I don't think the first part (everyone must earn a living) a "moral" position - it's an economic one. Fundamentally, economies are about raw materials and labor. The connection is getting tenuous already, and that's causing problems. -- there's certainly no raw materials, and very little labor, in the multi-trillion dollar financial industry.
There's plenty of room in that model for kindness to those who can't pull their weight economically (most entitlements), and for ensuring that basic needs are met regardless of individual economic output (e.g., minimum wage).
In a world where robots do all the labor and gather all of the raw materials, presumably their labor and raw materials will go toward making humans comfortable. Do we distribute that comfort evenly? The bulk of human history indicates that's impractical and impossible. Do we choose the current least-bad thing known to civilization: base the distribution of the robots' output on some kind of market system? If so, how does the market find a price? What do humans bring to a transaction involving, say, robot-farmed potatoes?
Most of the bubbles we've seen recently are due to markets being unable to find prices because they have become disconnected from fundamentals - either because the market has no fundamentals (the finance industry), or because the fundamentals have become distorted (housing).