[Soc2014] Official meta API

Sure, those arguments make sense for keeping the required interface in one place. If the required interface is not only flags, then as you say perhaps a renaming is in order.

(I think in general we should focus on "required interface" not "required mixin you must inherit". Sure, inheriting the mixin is a convenient way to get the interface, and some conveniences along with it, but there is nothing wrong with a field choosing not to inherit this mixin and just implement the required interface themselves.)