Homework helps reinforce the material learned in class. It's already a problem where there is too much material to be fit into a single class period. Trying to cram in enough time for homework will only make that problem worse.
Keeping the curriculum fixed, there's already barely enough time to cover everything. Cutting the amount of lectures in half to make room for in-class homework time does not fix this fundamental problem.
* due to either learning/concentration issues
* the fact that most lecturers are boring, dull, and unengaging
* and oftentimes you can learn better from other sources
making lecture longer doesn't fix a single one of these issues. it just makes students learn even less.
