1. This doesn't make any sense. On this reading, most any work is "optional" in that you had the option to do something else. But few people have the option to not work at all. If creating slop generates a decent enough ROI, and you have to work, then why is it waste? It may be waste to you, but for them it is an income. Just like there are entire industries or products I might personally think are a waste and yet make tons of money. In the modern economy most work is optional then. So what point are you making?

2. Yes, people get replaced at work all the time. And actually most employees who figure out who to maximize their own ROI (and thus their companies) get rewarded, not punished. If your slop code is "good enough" and you are moving the metrics the C suite cares about, your colleague taking far longer to create far less is obviously going to be punished.

If some sea change happens that replaces a whole class of workers, that is beyond the scope of the individual worker to think about. The modern economy can be viewed as one long process of automation, where most workers have been subsidizing their own eventual replacement, given the privileged position of capital over labor. This is historically obvious. It does not mean it benefits the individual to go back into some state of nature, or not reap what benefits they may gain from the prevailing system while it is still the one at hand.