dict is not a function, it's a class and the purpose of a dict() call is to create a new instance of that class.

The change you are proposing is also breaking for iterators:

>>> class Pairs(list): pass
... 
>>> pairs = Pairs([('a', 1), ('b', 2)])
>>> pairs.__dict__
{}
>>> dict(pairs)
{'a': 1, 'b': 2}

A change of this magnitude will need to be discussed on python-ideas and will require a PEP explaining why the benefits of the change outweigh its costs. I very much doubt that they do.

Will return only if it is not an iterator

You ignored the other point I made: dict is not a function, it is a class. dict() calls the function dict.__init__() which should create a new instance of dict (not return some field of its parameter). 


You also didn't justify your suggestion in any way. Why should this change be made?

Your point makes sense as it takes space to allocate for the new instance to just return another dict object. 
Then the attribute name at least should be meaningful.

Instead of __dict__ , __attr__ is more appropriate.

The vars() function already does this.

Changing '__dict__' to __vars__ will be much better.

Like len() calling __len__()

Can we change the title?

Why Github Issue Tracker is not issued?

Sorry, but I think there is a near zero chance that the language will be revised as you suggest. 

Marking this as closed. If you want to have more discussion, please take it to the python-ideas maillist.