It strikes me that mathematical writing is similar to using a language. To be understood you have to follow some grammatical rules. However, in our case, nobody has taken the trouble of writing down the grammar; we get it as a baby does from parents, by imitation of others. Some mathematicians have a good ear; some not (and some prefer the slangy expressions such as 'iff'). That's life.

Jean-Pierre Serre in letter to David Goss, quoted in: David Goss. "Some Hints on Mathematical Style," at people.math.osu.edu, accessed 08.2016