If someone insists that fully aligned text is better than left aligned text, tell them they are wrong. If someone else tells you that left aligned text is better than aligned text, tell them they are wrong.
MS Word: Align Left and Right on the Same Line – 1 MINUTE
If they’re both wrong, which is right? Alignment is only one small piece of the puzzle. What works for one design may not work for another layout. As with all layouts, it depends on the purpose of the piece, the audience and their expectations, the fonts, margins, white space, and other elements on the page. The most appropriate choice is the alignment that works for that particular design.
Traditionally, many books, newsletters, and newspapers have used full-justification as a means of cramming as much information onto the page as possible to reduce the number of pages needed. Although the alignment was chosen out of necessity, it has become so familiar to us that the same types of publications would look strange, even unpleasant, in a left-aligned text.
You will find that fully justified text is necessary, either due to space constraints or audience expectations. However, if possible, try to break up dense blocks of text with generous subheadings, margins, or images.