Hi Fkend
As the images show, you will loose boot space with the spare tyre. I feel it as I have spare boots, rucksacks and climbing gear in the car, however my feelings are the same as yours. Why have a AWD car that can go anywhere and nobody can come and help you if you get stuck. The loss of space in my opinion is vast. Further to this it will cost £400 odd for the spare.
In my opinion its worth the money to have the peace of mind.