Few phrases annoy me more than "it goes without saying". If it goes without saying, you don't need to say that. We're all busy people. Get to the point.
Picture by Anthony Easton
You could make a weak argument that the "it goes without saying" (and its equally irritating sibling, "it should go without saying") is being used for emphasis, or for rhythmic effect. That's rarely the case though. It's more often blather, inserted by someone who hasn't bothered to read over their work afterwards.
Take this sentence, which showed up as the top result when I searched for "it goes without saying" on Google News this morning:
If you’re making the effort to connect two spaces, it goes without saying that, in almost all circumstances, you should run the same flooring between both zones.
The same point can be made more effectively without the bloat:
If you’re trying to connect two spaces, you should almost always run the same flooring between both zones.
You can create emphasis more concisely with "obviously" or "clearly" or "evidently". But even that might not be needed. Any time you use this phrase, ask yourself: would the meaning change if I deleted it? Does adding that phrase make the sentence read better? The answer to both will be "no" most of the time.
Lifehacker's Mind Your Language column offers bossy advice on improving your writing.