> ...I'm just questioning whether this consistency buys you anything.
It buys you the same thing that API consistency always buys you: reduced cognitive overhead when dealing with a given API. :)
Edit: As GFK_of_xmaspast mentions [0] instances of non-trivial classes are not compatible with the default implementations of "operator <<" in ostream. So, you can try "ostream << instanceOfNonTrivial". If it passes the compiler, then you know that operator << is defined for that class.
So, no need to check the docs... just ask the compiler. :)
