Originally Posted by Mike L
What's so terrible about full justification? It's been used in books and newspapers for centuries.
And it works great and looks great when combined with all the other standard typographical conventions (66 letters per line average - clearly a problem for small screen readers, etc.). Professional typesetting software like InDesign or TeX also perform paragraph-level formatting, which means in order to get the spacing between words right so that the right margin is justified, the software will adjust the spacing ever so slightly amongst all the words in the entire paragraph, not just the individual line in question. That's a much more difficult thing to accomplish, but especially with lengthy paragraphs with lots of lines to maneuver, it produces much better results than line-level formatting. The Holy Grail of automated typesetting is page-level formatting or chapter-level formatting, but I don't know of any software package that does this at the moment. Typesetting software can also adjust individual character spacing, but that generally doesn't look as nice unless the allowable adjustment is kept to very tight limits.
Reflowable formats just as ePub or Mobi don't do any of this sort of complex formatting, so the text looks like crap compared to a PDF generated by InDesign or TeX. Thus, many people want to just have their right margins ragged so they don't have those annoyingly large gaps between words.