The Hobbit: Refusal of the Call

In The Hobbit by J.R.R. Tolkien, the main character Bilbo refuses his call to adventure because he doesn't want to leave his home, the Shire, or the comfortable life he's been living. Another reason he doesn't want to leave is because hobbits don't go on adventures, and he doesn't want people to think he's different.
I think that the significance of the refusal of the call is mainly to introduce the reader to the main character by revealing some of his character traits. It shows that Bilbo is a shy hobbit with both an adventerous side and a cautious side, and the cautious side usually wins, untill now.
The author also seems to enjoy bringing up the refusal of the call by saying.
" 'I wish I was at home in my nice hole by the fire, with the kettle just beginning to sing!' It was not the last time he wished that!" (Tolkien, The Hobbit 31)