I'd say the prevailing ideology is that the Artist should be able to articulate the True Meaning of the Work. For me, this assumption reflects the capitalist concept of the person as an autonomous, personally responsible individual. However, no work of art is the isolated product of a single person; it is in fact the result of a complex constellation of social relations (Marx's cherry trees in German Ideology come to mind, if that reference helps). Thus it makes no sense to ask the artist what the work "means", because the work is a product of more than the artist's individual intent.
I'm not sure what any of this has to do with art education. I work with Art faculty at my community college, and I have observed no correlation between being a gifted artist and being a good art teacher. Helping people develop their artistic skills is one task; creating art is another. I agree wholeheartedly that an art teacher must be able to effectively communicate about art; I see no reason why an artist should.
Sure, an artist could take the time to develop the writing and presentation skills, but then they have less time to create art. I say: let the visual artists create art! There are plenty of other people who can provide the narrative.
I recognize that this requires us to give up the idea of the artist as the one true arbiter of what a work of art means, but as far as I'm concerned, the sooner we abandon that bulwark of capitalist ideology, the better.
Miles