Speaking of 1955: if I had to pin down the year when the aesthetic values of print advertising started to falter.  As a photographer it's a bit of a personal irony - I do NOT want photos of food, I want beautiful illustration.  Example below.  I'd spaz out over if it was as illustration.  There was this relatively abrupt switch to photos, and food photography was straight garbage compared with now.

This beautiful Ovaltine ad would be shite if photographed rather than illustrated, as another example.