I think there is a misconception of what plugins do, and it looks like many people consider plugin writing as the logical continuity of regular rigging. In day-to-day work, however, writing plugins (and compiling, ingesting them properly in a pipeline, etc...) and rigging assets are as different as modeling and lighting (ok, maybe not that much^^).
I prefer, by far, someone who knows how to efficiently rig an asset in an animation-friendly way, than someone who will complexify everything just for the sake of feeling better at tech, forgetting that ultimately, the client is an animator, who doesn't care about the underlying logic.
Of course, this is just my opinion, but when I hire people (for a rigging position), I look at the skinning and deformation skills, the clarity of every control, how the puppet behaves, etc... not at whether the person is familiar with MVC, metaclasses, c++ or whatnot.
Again, just my opinion, I'm sure it can be different for other people ;)