By that rationale, all we -really- needed was ROTJ. After all they touch on the fact that there was a first Death Star by saying the one in ROTJ was the 2nd Death Star. They go over why Anakin fell to the dark side on Dagobah, and even recap why Luke was kept in the dark about Anakin.
I guess perhaps the divide here is between people who can't get enough Star Wars, and people who only want as much of it as is absolutely necessary.
A lot of your questions equate to "Who cares"?
Well -I- care.