Get things in perspective. When Coroneous published his books modern typesetting was not invented yet. In those days, there were no handheld calculators; to multiply or divide large numbers you use log tables or the slide rule. For scientific/maths publications, the best you can get for individuals and small organisations, was the IBM Selectric typewriter(does anyone know what this is? haha) with the appropriate golfball (bearing the typefaces). Only big publishers can afford the professional typesetting.
When Donald Knuth was writing a series of Computer Science textbooks he felt restricted by the existing typesetting technology. So he took time off to develop the TeX (from which you have LaTeX) and unleashed a revolution - professional typesetting widely available to the scientific/maths community worldwide. Knuth was a genius. Of course the advent of computers and now personal computers make all these possible.
I presume Jim Coroneous was, apart from being an excellent maths teacher, also an enterprising self-publisher. He did not have the resources of Addison-Wesley, John Wiley, McGraw-Hill etc. He probably did what he could with what he could get hold of. TeX was not available then. Even when available only large organisations could afford computers (mainframes, minis - no micros/PCs yet!!). He had no access to all the wonderful graphics/graphing packages that you all take for granted. So the result is the crappy terse dull boring presentation of his books.
A good idea would be to re-typeset in modern layout/fonts. I'm sure those still running the Coroneous outfit must have considered all this. But if you have a small and crowded book market (it's only NSW for heaven's sake - only a few thousand copies each year) you cannot justify that kind of investment. Besides the current syllabi for which his books are written are about to be phased out.
Those who can put up with the crappy typeface/layout, like jm01 & Slyhunter, have been richly rewarded by the excellent content.
[I have never met the man Coroneous. Out of curiosity I bought a few of his books - near new - for $1 to $3 only]