Besides common courtesy. I am obsessed with nail polish and having my nails done. One time I did think to bring nail polish on a flight so I could redo my manicure, but knew that it would be a terrible idea because of the fact that so many people are bothered by its strong smell. Especially in such a contained area, I think it's rude to expose other passengers to it without really giving them a choice. And even worse to ignore someone's request to stop!