For the record, let me just say that I'm -1 on adding this feature now. It's only a minor convenience while it's a fairly big change to the parser and code generator ...
That is a strong reason to deny the feature request.
... but most of all, Python's growth needs to be reduced. If we were to add every "nice" feature that was invented (or present in other languages), Python would lose one of its main charms, which is that it is really a rather simple language that can be learned and put to production quickly.
However, IMO this reason does not apply to the *arg feature request. Whenever a concept is already in a language, applying the same idea in other places does not make the language fatter or harder to learn. For instance, since generator expressions grow naturally from list comprehensions and regular generators, they are not likely to present a learning challenge.
... I appreciate the idea (which BTW has been proposed before)
IIRC, the conversation for the original proposal fizzled out without reaching a conclusion. So, resuming the discussion was probably a good idea. But now it has been officially zapped. Raymond