Some of what you are saying is the way to solve some of the problems I mentioned, e.g., poor video and sound quality.
Some more of what you are saying, e.g., about marketing, design, and e-mails to students, definitely would help. However, I assumed that such things were asking too much of poor schools and that, really, the HN readers who dug through K&R, etc. on their own with no marketing, design, encouraging e-mails, etc. didn't really need such nice hand holding.
But I will say, at some crucial points for me, some teachers did play a crucial role: The college I graduated from then had a quite good math department, and some of the teaching aimed at me personally in some of the courses was just excellent and got me going so that I could continue on to 'the next level' in math via independent work. Then for on-line learning, as progress is made on the first, and easiest work, many of the students will need some 'personalized TLC' or risk getting off track, slowing down, and stopping.
Part of such TLC will be overviews: That is, it needs to be more clear to students what the value, purpose, or promise is of various parts of the course.
Another part of TLC is that students need to write some things, e.g., homework exercises, term papers, something like lab reports, and have their work read by an expert and 'corrected'. E.g., a place to learn nicely polished skills in writing about functions, maps, mappings, relations, etc. is in a theorem proving course in abstract algebra where a good professor actually corrects some student homework. Then when work with functions, maps, ..., in computing, will get the notation and terminology right; without such TLC, often won't get those things right. E.g., earlier today I read a little about hashing passwords, and the material mentioned a function "between the hashes and
passwords". No, "between" is not appropriate. The usual description, and appropriate, is a function f from the set of hashes to the set of passwords. To be clear and not just picky, function f may not define a function g from the set of passwords to the set of hashes because there may be a password p such that there is no hash h so that f(h) = p. That is, the function f may not be 'onto', i.e., 'surjective' as at
http://en.wikipedia.org/wiki/Surjective_function
The level of clarity and precision available, useful, and often important is high, but students commonly need some in-person, TLC teaching in such things.
There's an old lesson in 'education': Get the student able to continue on in learning on their own. For that, usually some 'personalized TLC' is needed at a few crucial points in a student's development. To be really successful, the on-line approach will have to include some of that TLC also.