A little heavy handed, true, but, for the time, pretty courageous. Taking on topics that could be somewhat controversial wasn't the norm in the 80's, and tackling something like this with the rise of groups who practiced such things at the time was pretty bold for a cartoon.
I think it was one of the better efforts at bringing up an important issue. The Horde was a totalitariian regime, and, historically, one of the first things such regimes do is take control of the flow of information. Thus, the premise of the episode made perfect sense. And it wasn't so much preaching the value of every book ever printed as it was the value of a free exchange of information and ideas, a concept some folks need to be reminded of to this day.