Sometimes you just have to redirect one of the standard streams, for example, if you want to log all output to a file, but don't have any good way of doing that for whatever reason. This technique can also be used to redirect the standard stream and create additional streams for child processes, and so on.

An issue that I've run into a couple of times now is that when using a template class I've wanted it to encapsulate another class, using it for a number of operations. This isn't really a big deal, because any class that actually implements functions named what I call will work.