Why do photographers want their models to have a heart-shaped head?
I haven’t heard of this much until now (I’m more of a landscape and still life photographer than portrait), but I would assume that it has something to do with the fact that heart-shaped faces are symmetrical, have gentler, more flowing outlines, and are therefore easier to compose an attractive portrait around than a round or oblong head would be. Not all genres of people photography stick to this rule though, mostly the “Heart Shaped Face” thing is a rule of thumb for fashion photographers and those trying to make their models look conventionally “Beautiful”. An experienced, versatile photgrapher should be able to work with any shape of head and have the shot turn out just as well.