Have automation and technological advance been shown to have a positive impact on society and the economy or a negative one?
Would you rather work with a tractor or shovel?

Would you rather use one hand to work or two?...

Mathemathically the formula is:

$$EL  = \mathrm{GDP}_r$$

That is, efficiency ($/h) times hours worked per year equals the real GDP. Same is true for your personal life and personal income. Now, if efficiency decreases, you must either work more or live with less, which is not what anyone wants. Note that even as you increase your efficiency, there is little evidence that such thing decrease someone else's efficiency. So thus the result is income inequality and not "lack of necessities". That means, those with lower IQs generally earn less (since IQ is the primary driver of differences in efficiency between people)...

For the example in question, it seems that efficiency has increased, and at least temporarily the L term has decreased (even though the robot arm builders obviously still need to be employed). However, the cheaper robot arms make it easier for other sectors to accommodate people. So more likely result is a sectoral shift in the labor force, which is what historically has always happened. That is, the factory workers take pay cut, but demand for labor increases in a other sector providing a pay increase and more jobs to that sector. Historically L remains the same but E increases for the whole economy.