Why do they do it?

Why do cats chose the least favourable positions to sleep in?
Here are my two cats, Oscar and Felix, lying in the part of the back garden where its totally weeds, because the bees love them. The plants are now totally dead and parched from not being watered during the sunny spell and the cats insist on curling up there despite the house door being wide open, giving them access to comfortable sleeping places. When they do come in they will be scattering dead leaves everywhere. WHY?