Nice idea, BUT...
Not sure how a parser addition that supports it would go. Imagine this: if you did a one-line function:
def test(x): print(x)
Python could interpret it two ways:
`def` `name` `lparen` `name` `rparen` `colon`...
OR, it could see it as a lambda-like thingamajig and throw a syntax error. And, if someone accidentally wrote:
def (x): print(x)
Python should throw a syntax error. But it won't. And it'll take the person a tad bit to realize he forgot the function name. Whoops.
And, it just would be odd in general.