New game development students are usually so excited to have the opportunity to make their own games, that they fail to see the importance of understanding the tastes of an audience unlike them. We need to understand that as connoisseurs of games, developers are unusual because we live and breathe games almost everyday, and our perspective is not the same as most players.
In a way, casual players are akin to "muggles" - to borrow the term from a popular series of books about a wizard with glasses and a lightning bolt scar on his forehead. Many long-standing communication schemes, while intuitive to gamers, may be enigmatic to casual players.
Being able to design a game for "muggle" (non-gamers) should be a key part of a designer's toolset. In this article on Zam, designer Zach Gage points out some interesting approaches for over-coming this issue - the use of every-day objects.