It is so easy to get caught up in the day-to-day mundane distractions from what is really important in life. Sukkot is a holiday of immersion that reminds us of the reality of this world as a transient place. When we move into these shelters to eat, sleep and essential dwell outside from our permanent dwelling space, it is impossible not to recognize how vulnerable we are in this world and appreciate how much protection from the elements we receive on a daily basis.
For a deeper look at this concept enjoy an article by Rabbi Mendel Weinbach, shlita.