Andy Weir uses profanity to show strong emotions and amplify the feelings in all of the characters.
Things we don't necessarily like to begin with, such as the disco music Mark Watney listens too, will become things we like if we are exposed to them long enough. The disco music also shows a connection with other humans; a need that all humans have.
Friendship is in this book. The Ares 3 crew think of Mark Watney as a friend, espeically Commander Lewis. The're willing to risk their own lives to save him. They face the possibilty that they might not get home, and yet they still risk everything to rescue Watney, a fellow crew member.
Much of the story of The Martian is told through an anecdote. Andy Weir wrote the book is such a way that it tells the story from Mark Watney's point of view, which is quite often an amusing point of view.
Mark Watney is an archetype of human spirit, and will power.
