Again, I agree with you: all the points of your first paragraph are valid to some extent.

But sometimes a totally dumb and closed system like an iPad is a feature. It is so simple that Students (from 10 to 19 years old) and teachers (from 25 to 70) can use it. It is so closed down that the teachers can easily and reliably distribute tasks, apps, restrictions and don't have to deal (they will stand no chance) with students tampering with their systems.

It would be great when all school subjects would address FOSS and the impact of closed systems on society but they also have to address their core curriculum. Here I see the possibilities that the iPad opens up as a net positive.