I don't necessarily disagree, but...is this worse than what we already have? My argument against this sort of this for a language like C is that "do what you think I mean instead of what I say" might not actually result in what I _actually_ mean if the compiler guesses wrong, but undefined behavior isn't generally going to do what I want either, so I'm not sure this would be any worse.
Some people depend on undefined behavior, but there's generally not much sympathy for it, because it is in the name.
On the other hand, many people have depended on interpretations of intent.
Changing the behavior of one is much easier for the community to swallow than the other.
An easy example is how early versions of IE failed to correctly implement the box model for sizing elements. For backwards compatibility reasons, IE6 and on would revert to the old, incorrect behavior if parsing the html document put it into 'quirks mode', and later on this behavior was added as an optional CSS box-sizing property.
