Yes, it would be necessary in case you ingested a poison or something that would pose a physical risk (blocking your oesophagus or irritating your stomach). Rats don't vomit, for example, and they survive that way but if they ingest a poison, they die, they can't v* it out. So having the ability to do so is actually quite useful if rarely used nowadays for that purpose. It is also good in case of illness to remove the virus or bacteria that cause irritation. Sadly, a lot of sv* are actually caused by irritation of the small intestine so by the time you v* there is no use anymore as the pathogen has moved out of the stomach already.