In the very small sample group of people that have given me feedback about meld3, I've found that it's enough just to not document "loudly" the fact that you can use the _ElementInterface API against nodes. This is in the docs, but people don't seem to read closely enough for it to register; they assume the API is only what's explicitly spelled out in README.txt. Because of this happy accident, I'm not sure it would be useful to take active steps to legislate prevention of the use of the _ElementInterface API as a result, because it's often pretty handy if you know exactly what you're doing (e.g. you promise not to whine about coupling once you do ;-)

I'd agree that if this is the tact that we take, the "attributes" method might go away (due to the need to use the class keyword a lot) in favor of manpulating self.attrib directly. Or not. ;-)