The iconographic stylization persisted in Italy in some regions due in part to the fact the some parts of Italy remained under Byzantine rule until as late as the 11th century and the painting style continued, passed down by tradition.
Four More Images of St Francis From the National Gallery London: Three Good and One Bad!
Baroque artists painted so that the pictures pops into focus when viewed from the distance of approximately 3 times the distance of the widest dimension. So this one is meant to be viewed from approximately 30 feet away. At this distance the viewer can see the whole painting without having to scan the eyes over different parts of the painting.