Why do we do that?

[JJ]

OK - here's another "stupid" question: Why do we indicate a foul tip on strike one or strike two with nobody on base? Does it really matter? Why indicate a "catch" at all on the routine fly balls that everyone sees are catches? Why indicate outs on ground balls that everyone knows are outs?
Sorry...my season is about over and I'm grasping at "stupid" straws...I'm going to have a(nother) cold one and find the la-z-boy...