[pdonis]

And ``key in dict`` wouldn't work any more

The "in" operator is actually a separate operator; it doesn't depend on the dict iterator implementation. So you could keep the semantics of the two separate.

However, if the dict iterator semantics were changed, it would make sense to change the semantics of "in" as well--and since it doesn't really make sense to change the semantics of "in" (if you're asking if something is "in" the dict, you mean the key), that would explain why the dict iterator semantics are the way they are: the dict is a container of keys, not key-value pairs.