A lot of patterns (e.g. from GoF) are unnecessary or can be implemented with less efforts in dynamic-typed languages with functional flavor. In fact, a lot of patterns are "built-in" into python so if you write short and 'pythonic' code you will get all the benefits for free. You don't need Iterator, Observer, Strategy, Factory Method, Abstract Factory, and a bunch of other patterns that are common in Java or C++.
This means less code to write and (much more important) less code to read, understand and support. I think this is the main benefit of languages like python. And in my opinion this greatly outweighs the absence of static typing. Type-related errors are not often in python code and they are easy to catch with simple functional tests (and such tests are easier to write in python than in java for sure).
