Yeah, I've heard mixed reviews of those Hill trecks. Supposedly the system has been reformed to space those groups from eachother, but there are so many of them I don't know if that's possible.
I've been to Chiang Mai twice but I've never done the treck. I did, by car, visit 2 of those human zoo/villages. One was that pushy trinket situation. Then, at the longneck lady place, they just ask a fee before you go in. I think it's a bit more honest and less stressful. Look, they know you want to see them, it's somewhat invasive, so you may as well pay for the privilage. Then, once you're in, there's no tension or pressure. It was very relaxed.
I don't think it's totally wrong. It's natural that people would want to see how other people live. For them to set up a little part of the village for that purpose, and then charge us to see it, I think affords them a little control and protection. Then again, I don't really know all the real details of what's going on, but it does seem more respectful that having foreigners just show up, take photos, and leave without giving something back. It just acknowledges the reality of the situation.
It's a lot like Lucky Chengs.