Incremental change is good as long as the increments can themselves be changed. When you're promising indefinite backward compatibility, it's important to be VERY confident of each change before committing to it.
It seems like the price of all these small incremental changes in Python is that the language as a whole keeps falling further and further away from the 13th item in PEP20: "There should be one - and preferably only one - obvious way to do it." Also, for that matter, "Never is often better than *right* now."
