One reason I'll still use pi
Every so often, someone brings up the thing with tau (蟿) versus pi (蟺) as the fundamental circle constant. In general I find the discussion wearisome because it usually focuses on telling people they are stupid or wrong for choosing to use one constant or the other. There are more productive uses of your time, I think.
But for a while I have wanted to add just this one thought to the conversation and now is as good a time as any.