This particular professor is actually big on the idea that when we teach high school we're likely gonna be teaching predominantly kids who are uninterested and/or reading below grade level. His day job is teaching at just such a high school. He's talked a lot about the importance of engaging with the text at their level, not doing the intense kind of stuff we do at the (under)graduate level, and not being afraid to do stuff like build the Walls of Troy out of sponges with the kids to get them engaged with the material.

Presenting lessons is partly to give us experience in doing that, in engaging with texts with intent to engage others, and to think about the different learning styles people have and the different ways one could approach material.

Designing essay prompts is in large part to force us to think about the realisticness of what we're asking the "students" to do -- we not only have to answer our own prompts but should also be keeping in mind who it will be who will be answering these prompts.

Student teaching is required to get a teaching certificate, because you really can't know what's gonna work until you actually try it -- and of course that's always changing with the students -- but i do think there is value in forcing you to do practice of a sort, rather than just saying, "Here's a class. Teach it."