You're right on trusting the core developers, but "for a reason" type arguments are not the way to do things. I love Python because it's so practical and manages to stop codebases from devolving into overengineered incomprehensible messes, but I hate tons lots of things about it, and more generally I hate its "worse is better" approach (http://www.jwz.org/doc/worse-is-better.html) to many things (because for Guido, if "worse" is "simpler to explain and implement", he always chooses it, always implementation simplicity over nice "interface" features and also over "interface" consistency... I almost want to shoot the man when I read arguments like http://www.artima.com/weblogs/viewpost.jsp?thread=147358 coming from a very smart person like him). OP's complaint is valid imho, consistency is f important, because small inconsistencies pile up and make a language harder to learn (yeah, you don't notice them once they're in your "muscle memory", but "learnability" is important for a language and this is why I like Python and I hope it doesn't lose this quality by slowly accreting inconsistencies). Hopefully his blogpost is a message that reaches Guido and the core developers and nudges them even a little bit towards a better path!
I just wish someone could find the old discussions...
The main argument I could see against empty set literals was how wrong it felt adding it to the grammar. Even adding 3 lines of code for the feature, felt like it was just creating chaos in a zen-like codebase.
imagine that the "chaos" you are adding to the implementation is actually subtracted from its "interface" and consequently from all code that will be written thereon... sometimes you need to "add complexity"/"destroy order" to create more order at a higher level :)
Really, you should trust the core developers on this one. Empty set literals are missing from Python for a reason.