For text that stretches across an entire page, I don’t really care. But if you have 2 or more columns, please, pretty please use ragged right and not full-justified text, unless you are printing in 9 point or smaller.
My reasons have been described by others above. I also note that the people I work with who have the least knowledge of design principles and modern trends always think full-justified is better. Artists, trained designers, and people who keep track of trends in design and layout tend to have a strong preference for ragged right.
Interesting you say this… I work for a lawyer (and was raised by one), and I have always preferred justified text. I wonder if the two could be correlated. I’ve never written in columns, but when writing letters, papers, etc. I justify the text. It just looks so much cleaner to me.
I grew up in the era when justified vs. ragged-right text marked the distinction between store-bought and homemade text. Justified text was what appeared in books and magazines, and, as such, was the sign of something that had been professionally produced. Ragged right was what any old schlub could pound out at home on a typewriter. Thus, I considered it so. friggin’. neat. when I first got to use a word processor that would let me produce my own justified text.