I don't know if this qualify as misery tourism, though I can't lie, as someone who have been there, this framing gave me pause.
I can only speak for myself, but I didn't went there to I witness misery or feel superior to anyone, and it is definitely (and obviously) not the goal of those tours.
As I already said in this thread, I'm just the type of person who always look for new and different experiences, and North Korea is pretty damn different, more so than any place I've ever been to.
I will concede that this is a pretty self centered point of view, but I can always lean on my favorite Mark Twain quote (which admittedly, at most is only partially applicable to a North Korean tour, and even that might be stretching it) - "Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome, charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime."
But I might be just rationalizing me love of travel.