Why does Daft Punk wear masks?

Answer 1

Daft Punk have said that they donned their robot masks to easily merge the characteristics of humans and machines. However, Bangalter later stated that the costumes were initially the result of shyness. "But then it became exciting from the audiences' point of view. It's the idea of being an average guy with some kind of superpower."

Answer 2

Daft Punk wear helmets and robotic clothing for several reasons. One, because they do not wish to be recognized as Daft Punk every time they go somewhere; they like their privacy, and wearing helmets is a stylish way to keep their privacy. Second, by wearing robotic suits, they've established their own personal unique look: a type of icon to quickly recognize & remember Daft Punk. Third, their music is somewhat robotic sounding, so their robotic appearance is no less than fitting. That's mostly why they wear helmets: to keep their privacy, to keep you coming back, and because it fits the style of their music.

Now if you want to know how they got the idea to do that is a whole different story.