The README file should only have the a synopsis of what the module does and a simple explanation of how to install it if an INSTALL file isn't present. Its the job of the documentation within the module that should explain usage. Having that explanation in the README file is rather redundant in my opinion.
extracts the POD from the module and creates a page that can be viewed on their site for more information. You should be looking there for usage rather than the README file.
It's up to the author of the module or those who take part in its creation to properly document it. Going through some of the modules on CPAN I do see that some of the documentation provided with them is very poor. While others provide an explanation that allows a user to get it right the first time without mucking around.