"There is *no way the editor can handle this correctly*. "

Funny. Mine does. You paste it in, select the code you pasted, type tab, and it indents it one level. Correctly.

They did fix it. Now you can't mix tabs and spaces anymore. So it's fixed.

"Doing so would even retain backwards compatibility with prior versions!"

Eh. No. It would require you to have brackets, which would break backwards compatibility.

Yes, the indenting thing is annoying. In the beginning. Then you get used to it.

The thing with the indentation is that because you indent anyway, the brackets are simply superfluous. Getting rid of them makes the code more readable. Also, this way there is no war about the One True Bracing Style, since the brackets aren't there. ;)

"it's guaranteed to be "good" programming?"

No. But some common newbie bads are no longer possible.
Here is one example:
http://regebro.wordpress.com/2008/06/06/python-3-will-make-you-a-better-programmer/