My daughter recently started dating, and a Shidduch (match) was suggested. The boy's family requested a picture prior to deciding if they want to proceed. I felt that this was inappropriate for reasons of Tzeniyus (modesty) amongst other possible reasons, such as Bain Adam Lechavairo (treating others properly), photos not showing actual personality thus potentially leading one to saying no to ones Bashert (destined match), and the fact that if the Shidduch does not work out they still have the photo. Does any contemporary Gadol (major authority) discuss whether this is proper or improper?
Yes, both R. Chaim Kanievsky and R. Dovid Feinstein have expressed opposition towards this practice, because one can't get to know a picture. See here.