Is "Needless to say" ever worth saying? [closed]

Obviously, you are wrong.

First off, I don't need to point out that the majority of everything we say or write is superfluous, redundant, or pointless. Very, very little is really "worth saying". However, it is not a rule of English (or any language) that anything that can be removed must be removed. Pointlessness and redundancy are not wrong, they are merely pointless and redundant.

Second off, it goes without saying that "needless to say" is neither pointless nor redundant. It actually has a meaning and a purpose. It flags an otherwise unflagged statement as obvious, and consequently can be used for anything from emphasis to apophasis, from softening the impact to pumping up the condescension. Just compare "ρ = r(cos α + cos β + cos γ − 1)" to "Needless to say, ρ = r(cos α + cos β + cos γ − 1)".

Lastly, I don't even want to mention that "needless to say" is not the only phrase that is used for apophasis. There are many, many, countless other phrases, idioms, wordings and constructions that do the same thing. And not just in English but in absolutely every language. So any child can see that it is rather pointless to single out this particular phrase.

"Needless to say" is often used to bring attention to something which should be obvious to everyone, but (in the speaker's mind) isn't necessarily obvious.

For example, you might say:

We ran over budget again this quarter. Needless to say, if we can't stay under budget, we'll all lose our jobs.

The speaker in this case is using "needless to say" to call out the (obvious) relationship between staying under budget and keeping a job.

Needless to say, (see what I did there!?) "needless to say" has no place in concise or technical writing. However, it can be an effective tool for certain purposes.

Adding the phrase needless to say can have at least a few purposes.

First, it is one of those emphatic phrases used to give special weight to a particular observation.

Your mother stopped by and cleaned the house again. Needless to say, I can't find anything now.

This emphasizes the seriousness of the conclusion, even though it may be obvious from past experience that it may often happen as a consequence of the premise.

Another use might be in the recitation of a series of events, even stating the obvious for completeness. For example, a pilot explaining what happened before a plane crash.

The engine fire light went on. We looked outside and saw flames. Needless to say, at that point, we had no power and the hydraulics didn't work. That is how we happened to crash.

As a form of phatic communication, it may be used out of politeness while stating the obvious, reducing any perception of condescension.

Needless to say, your age will be a concern the next time you renew your license.

You will have to look at the full context to see if it is genuinely unnecessary or has an implicit purpose, but there are reasons to use it.