I notice a lot of people saying that they do not want their kids to be sarcastic, and they give advice as to what to do to prevent your kids from becoming sarcastic. What's the big deal about being sarcastic? And no, that was not sarcastic.
Sarcasm is a linguistic device and it is hard to see what separates it from others that accounts for why it is to be avoided. Let's compare as we dare sarcasm with onomatopoeia. The latter is the formation of a word via the imitation of a sound ('boom', 'plop', 'zing', etc.). I take it that there are not people out there trying to get their kids to avoid onomatopoeia.
There are contexts in which sarcasm is inappropriate, yet the same is true of onomatopoeia. In fact, there is a great overlap as to which contexts these are. So, this cannot be the reason that sarcasm is to be avoided.
Sarcasm, you might think, has an annoying sound to it when said with that sarcastic tone. First, it is not clear that sarcasm requires such a tone. Second, many instances of onomatopoeia are instances of annoying sounds. After all, who likes to hear 'plop' or 'squish'? So, this cannot be the reason that sarcasm is to be avoided.
It may be true that sarcasm is often employed in a negative way -- used to disrespect someone. It can't be the mere fact that sarcasm can be used in such a way that it is to be avoided since many linguistic devices that are presumably not to be avoided *can* be used in this way. Onomatopoeia can be used in this way. Further, sarcasm needn't be negative in this way. I could utter to a fellow employee, "yeah, your not going to get the promotion" sarcastically, yet what I say is far from negative, in fact it is a complement to my associate. So, sarcasm needn't be negative in any relevant way. We are left with the claim that sarcasm is often used in a negative way, but why should this affect whether or not it should be used at all? If most people used pencils to poke themselves in the eye, it would be a bad thing, but nothing would follow regarding my using a pencil.
As a result, I can see no reason why sarcasm ought to be avoided. It should be responsibly used, but this is a different issue -- one that takes a lot more thought.