Very few people are actually suggesting that automation is bad, per se; the concern many people have is that the rate of change needs to be managed such that significant numbers of people aren't left behind. People can only retrain so fast, and some people will never be able to effectively retrain. Automation that suddenly puts them out of work needs to account for what they're supposed to do, and hopefully it's something better than "sit at home and drink themselves to death / overdose on opiates / engage in crime".
I'd rather intentionally put the brakes on automation, even though it's a hit to efficiency (and depresses the value of labor -- automation makes human labor more valuable over time), if the alternative you get with unlimited automation is a massive disenfranchisement of working people and consequent destabilization of society.
Better to keep some technologically-unnecessary jobs around than to live in a society constantly teetering on the brink of a violent populist uprising. All the efficiency gains of that automation are going to pale in comparison to the damage and loss that will happen during one night of rioting by the now-unemployed proletariat.