The reason pyOpenSSL was created is that the SSL support in the socket module in Python 2.1 (the contemporary version of Python when the pyOpenSSL project was begun) was severely limited. Other OpenSSL wrappers for Python at the time were also limited, though in different ways. Unfortunately, Python's standard library SSL support has remained weak, although other packages (such as M2Crypto1) have made great advances and now equal or exceed pyOpenSSL's functionality.
The reason pyOpenSSL continues to be maintained is that there is a significant user community around it, as well as a large amount of software which depends on it. It is a great benefit to many people for pyOpenSSL to continue to exist and advance.