One of my main frustrations when I first began teaching languages was the negative reaction from parents. This then fed through to their children who also announced their opinions very loudly during these lessons! In the schools where I was teaching, language learning was introduced in Year 3 or 4. Students would do two or three years, one lesson per week for around 45 minutes. Many of the high schools that these students went to did not have languages as a subject, or they had a different language. I found it very difficult to justify my position. I was absolutely committed (and still am) to the job that I was doing but it really deflated me listening to parents and their students complaining about having to "learn a language they will never need to use".
I would try really hard to be positive and had information to give to parents about the positives of learning a second language. In the end I gave up. Not because I didn't care, but because the parents didn't care.
There was no point in trying to justify my position when they would not listen to what I had to say, or read any of the information I had researched. So I would simply smile and suggest politely that they speak to the Principal. It wasn't my place to justify my occupation. When I stopped getting upset or frustrated I found that the negative chatter reduced. There was still a comment every now and then but as I didn't let it get me down, in some ways their words had no effect on me.
Parents all want the best for their children, but sometimes they don't see a benefit if they have not experienced it for themselves. Don't give it any oxygen and it won't be an issue!