Letting him stay in the crate all day would not be "giving in" and letting him "choose." Is he fed in the crate? Could you lure him out with a treat, and positive attention? Try that, it sounds like right now you just get him out of the crate and he goes straight outside for the day. Has anything changed outside to make that a negative thing? Any other recent changes in the household? How do you react when he refuses to come out? Has he been to the vet lately to make sure nothing medical - like the onset of arthritis or something - could be affecting his temperament?