For each "wart" the author has a "What can be done?" section, but no suggested solution involves a major redesign of the datetime module.
The author complains about non-obviousness of strftime and indeed, for users without C background, neither name nor semantics is familiar. But the proposed solution
>>> time.format('{{hours}}:{{minutes}}:{{seconds}}', 1090)
'00:18:10'
Does not look like a big win over the already available solution:
>>> '{t.hour}:{t.minute}:{t.second}'.format(t=datetime.now())
'12:37:38'
Overall, while I agree that there are a few warts in the datetime module, I have not seen any serious enough to warrant a major redesign or even any non backward compatible changes. Maintaining backward compatibility in the datetime module is indeed non-trivial, but this is the way I think it should be developed.