1. Children are often immature. Research has demonstrated pretty definitively that students, even those in high school, are physically immature compared to adults. The US Supreme Court even cited such research when it ruled that those who commit crimes when they are under the age of 17 are not eligible for the death penalty - the parts of their brains that govern mature thoughts are not as highly developed before age 17 as they need to be to make important decisions about their actions. Thus, while I am all for putting "students first" and catering to their learning needs and proclivities, ultimately students are not as aware of what is best for them as they think they are. They would rather hang out than do math. They often fail to see the long-term consequences and benefits of their actions today. They often lack perspective about how something they learn in algebra or English class may be important to them in the future. They certainly don't appreciate that their failure on a test can cost a teacher her job in this climate. Thus, they need adults around to help guide them past their immature decisions so they can learn how to make mature ones as adults.
2. Students have little tolerance for boredom. Ask any classroom teacher what happens when a lesson is boring. It's a nightmare! Students become restless or sleepy (depending on their current level of sleep debt, which is likely large!), and the class ceases to become a learning environment. When students disconnect from the class experience, they are usually not polite about it (see point #1). They typically play around with other students or spend precious energy figuring out ways to distract the teacher from teaching, mainly because that's just funny to them (again, see point #1). Thus, putting more students into a classroom where the teacher cannot give more individualized attention is likely a recipe for disaster. It would save money, and perhaps that's really the goal of that reform recommendation. But my bet is that it will not lead to greater learning. It will just lead to more management. To manage large classes, you tend to sacrifice the needs of the individual for the goal of the masses. This classroom setup will produce boredom for someone, and you just have to hope that someone is the more mature kid in the room.
3. Students can smell weakness. The best measures of effectiveness of teachers are not their value-added scores or their school's AYP status. The best measure is the word-of-mouth the students give about that teacher. People would ask me, "What kind of teacher were you?" My response was always, "Ask my students." I always felt I did well in the classroom because my students did well on their tests, and they seemed to be pretty well behaved when they were with me. But I would keep my ear on the ground to hear what they said about me behind my back. I would also solicit periodic anonymous feedback about my teaching from them. Usually, they were pretty honest with me. I'd hear all sorts of helpful suggestions like "You should not give those types of quizzes any more - they're impossible!" or "Sometimes you are very sarcastic, and I'm not sure how to take it." I also got immature suggestions like, "We need to have more free days." I knew from this feedback, though, what I really needed to fix. When I flubbed it up in the classroom, I would hear about it from my students. They had little tolerance for bad teaching on my part, and they made sure I knew it. And I appreciated it because it helped me keep on my toes.
Adults are usually much more mature and polite than our students. They can think through decisions and not react with immaturity when things are challenging. They can be polite in the face of a boring meeting or continuing ed class. Adults can be much more forgiving of weakness in the workplace, since people's livelihoods are at stake.
I think that education reformers need to stop thinking about students as miniature adults and start remembering what it was like to be a child or teenager. Motivating a room full of immature teenagers is not like motivating a group of people in a large corporation. The approaches are necessarily different. The amount of work it requires is necessarily greater.
To reform education, you must not put students first. You must put yourself in the students' shoes and remember what it was like to walk around in them. Then, you can start formulating plans to help them move out of their sneakers and into some wing tips.