While flush right looks nice and tidy, it can be problematic if the article has a lot of technical terms and lots of long words. Then, although the finish of each line is nice and tidy, there are wide gaps between words that cannot be easily dealt with.
Hand in hand with the ragged/flush debate is the hyphenation question. Again, I prefer no hyphenations unless absolutely necessary. Hyphens may be necessary, however, if your client insists on flush right but at the same time has a lot of multisyllabic words. Without the hyphens, the gaps between words distracts from the message the article is supposed to convey.
The reason I like a ragged right is that your eye naturally follows a string of text with varied endings for each line. Your brain doesn't like to figuratively slam up against the right hand margin while trying to process what it is reading. Similarly for the use of hyphens. The brain has to stop and re-check the word because to your brain, the hyphen acts as a stop in the middle.
Stylistically, there are many things you shouldn't do but very few that are absolutely forbidden. The main goal every time is to have an effective product that leaves the end user feeling a little bit better at the end for having been part of the experience.