Why does society reward “putting on a face” (i.e. professional, social, etc.) rather than dealing with things that are real, messy, human?

Ahhh. Fake smiles, white lies, and contextual personae. These social falsehoods may seem bad but in fact help keep social situations and relationships strong. Unlike “big lies”, these “little lies” in effect say that our relationship is more important than anything else. Also, people can be hesitant to bring up the “real,” because it risks causing someone–maybe even the speaker–to lose face.