I'm confused by this.
Why would I want to take an internship where I was considered a net-negative?
If the institution of learning that is placing these interns is slotting people into internships, and they are worth than useless -- net negatives, as you say -- where is that institution's accountability here?
Why would any intern walk into that situation? Why would a company take them on under those circumstances?
Sure, I would expect an intern to be very inexperienced, to need mentoring, to need training, but the idea is that I'd get free or nearly-free labor in exchange for some of this required mentoring and training... and potentially have some partially trained future employees in the pipeline.
It would be, I think, crazy to expect that interns walk in already completely hammered into the appropriately shaped pegs to slot into jobs.
I'd fire the person who fired the interns -- I mean, how much time and effort on the part of the people who arranged those internships, did that person waste by being a dick? How does it affect the department plans to get work done with these interns?
If the answer is "not at all," why the !@#$% do they take on interns? Some kind of tax break thing?
When I was an intern [sometime mumble mumble nineteen-eighty-mumble], I spent a year earning a tiny stipend and working crazy hours because I did tedious work that my organization wanted done but no one had time or inclination to do. I learned a lot, including how to work with people in my department, but I did not learn "I'm worthless and should never question authority because I'll be immediately fired."
And, p.s., I've worked with and supervised interns before in several different workplaces.
Some internships are basically a form of charity, the mild negative effect on everyday work is at least partially balanced by the longer term potential of an intern becoming a good candidate for a staff position or by the positive effect on reputation of taking such interns.
In my specific area, the interns are a net-negative for the time they're with us but when they work with another group, I think they're (minimally) a net positive.
That's a big assumption to make. I doubt the company ever tested whether their business made more or less money without dress code.
If the interns placed so much stock in what they were required to wear during their internship, they should have asked about it during the interview, and withdrew themselves from consideration upon learning of the dress code.
But no, they felt that the company should change its policies to suit them. Because they're that darn special.