Of course people should get paid if they were promised an internship but end up doing menial labor. But they have a simple solution: they can just walk away from their unpaid internship without losing anything. If you voluntarily stay in an unpaid internship, presumably you are getting something out of it.
The insidious effect of this rule will be to place organizations providing good unpaid internships at a much higher legal risk, because the organizations that provide them now have to worry about getting dragged into court by a disgruntled intern for back pay. That not only means they are going to be less likely to have interns in the first place, it also means that interns who can't clearly contribute at a high level from day one have to be kicked out right away.
Negative. What this means is that internship offerings will have to be more concrete in what the learning outcomes will be and also not replace low skill work (e.g. go clean the bathroom - unless you are in zoology and it's animal bathrooms) for interns . Will there be less offerings? Maybe a little but the internships that do stay will be more valuable for both the student and business in the end.