If we let it slide for members of the middle class then it will eventually lead to an ever greater portion of the population unable to earn a dignified quality of life for their work.
Engineers, web developers, etc. are paid very well now, sure, but as more and more people enter that industry and those skills become more commonplace, do you really think things will remain that way? As more of the industry is able to be automated, do you think as many people will be able to stay in the middle class?
And when people in the middle class start accepting things like company housing, contractor jobs over salaried employment with benefits, longer working hours, etc. what do you think that will do for the lower classes of society? I think we're starting to see that now with pseudo-jobs like Favor and Uber, which have even less security than the service industry has traditionally had.
It's not just about facebook engineers or whatever, it's about society as a whole. The problems faced by society are largely the same, different only in degree; we shouldn't separate them up and devolve into infighting because these yuppies or whatever can afford something like the quality of life an average worker a couple generations ago could have, and that's considered fabulously well-off now. If industry starts treating middle-class people badly, they're treating lower-class people worse for the same reason. The whole scale slides.
A strong middle class with strong labor rights helps all of society. We can't do this crab bucket thing where we say it's foolish to defend people with some amount of privilege because there's people over there who are worse off--what is the ultimate end of that strategy, a search for the most downtrodden person on earth and delay all progress until we work our way up the list?