DFC your statement that one must be a qualified instructor to teach for the instrument rating needs to be more clearly explained.
Here in Canada the requirements are plainly outlined in the CAR's and are experience related only, there is no requirement for one to hold a certified flight instructor rating, however you must hold a commercial pilots license or higher.
Actually if one looks at it logically it makes perfect sense to learn from someone who has actually been flying airplanes for a living IFR for thousands of hours rather than some newly minted flight instructor who has never been in a cloud in his / her life and their only qualification is they have been programmed as a " flight instructor " by someone who has never flown in an cloud either.
The way I look at it getting my flight instructors rating renewed would be counter productive for me as it would be getting something that would only qualify me to earn lower wages for my instructional skills.