It is stupid to create polls if you know the answer you find will upset you in any way. That just seems silly, like you are setting yourself up to be upset just because you want to try and argue or disprove soemthing that you know is a fact. It seems unhealthy.
A lot of people create polls simply because they know it will upset other people on the Internet. Sometimes, watching a passionate discussion about a thing, simply because it dared to exist, can be absolutely hilarious. But in a more general sense, if polls are ticking you off, then you probably shouldn't be asking questions if you can't handle the answers.
The opinions are still useful. If I disagree and become offended, I should be asking myself if I should be offended. The answer is usually no. I don't get offended easily, so this usually doesn't bother me anyway. It's good to learn how to handle these situations when you disagree as well. The more you think about the opposing view, the better you'll be able to defend your own.