I hear where you are coming from, but it sounds a little like "We didn't have warnings in the past, we always checked using defined. Why should we switch to using them now?". To me the difference is between having to check everywhere and maybe getting bitten bad if you missed something, versus getting a noisy failure if something unanticipated happens.
In most cases I'd rather have a noisy failure and deal with it than a quiet failure that may just plough on and destroy the world.
True laziness is hard work