I am not really a fan of the Picture thread, since none of us here is dedicated to go looking for them. Its more like "I see it, I like it, I share it" for me.
Also posting it into chit - chat in between the conversation it freshens up the conv. You look at pretty waifus while reading walls of text, thus breaking up the monotone text a bit. Whereas if we made a thread just for pictures there wouldnt be much traffic once the novelty wears off, plus making a thread would required to dedicate time just for gathering a posting those pictures.