I think that some things definitely need to be unlined (if the fabric has properties that can only be used when unlined, like fresco like cloth). CBD suits should probably always be lined so the back always drapes smoothly on the waist/hips without catching. Everything else seems like a toss-up and a matter of preference IMO.
When I do unlined, I have a strong preference for 1/2 lining as I only really feel the benefit of the unlined option on the back of the jacket. The fronts are canvassed and lining makes little difference.