I do not understand why people who get serious about it want so badly for it to be called table tennis. Ping pong is a way more fun name, and table tennis just seems to make it out to be a smaller, inferior version of tennis.
In the context of competitive events, it probably makes sense to use "table tennis," simply because there is one notable event that uses "ping pong" to refer specifically to different set of rules and equipment (the World Championship of Ping Pong).