The thing that bugs me is that if you ignore the error (by simply not checking for it), it's still there, possibly insidiously corrupting runtime state. Imagine trying to debug a file format corruption that happened because some obscure part of the code tried to add to the format and instead errored (silently) and added garbage and then the code just kept chugging along until the state REALLY messed things up.

The thing many programmers don't seem to realize is that a program is a model of a design in the programmer's mind. If the model goes off the rails of the expected design/behavior in any way, that should be considered very bad ASAP... or as many languages treat it, "exceptional".