I can't think of a good reason to have your fridge controlled by a switch. It's not like you are turning it on and off a ton. I can think of more reasons not to run it through a switch (like accidentally hitting the switch and turning it off while your fridge is full of food) than I can for doing it.
Also consider that your switch has to be rated for the current draw the fridge produces, otherwise you need to run it through a relay.
I ran mine straight from the battery and just leave it plugged in. I turn it on and off using the buttons on the fridge. Worst case if I forget to turn it off someday the fridge will shut it self down before the battery gets too low. I regularly leave it on overnight when traveling and it hasn't been an issue.