I think you would find a lot of instructors who are grossly underprepared to teach instrument flying. The issue is not the experienced instructor who simply didn't have time/money/desire/need to had the II onto his certificate. In a perfect world this perfect person would have good instrument flying experience and teaching experience. That kind of person would be a perfect candidate for an "automatic" CFII. Unfortunately in practice you would get a fresh minted CFI who has never seen a cloud, flown a real IR approach and hasn't flown more than 1 IFR XC (the single required one for the rating), and on top of it probably hasn't taught anything yet. In my opinion it takes more work to teach an instrument student because of the attention to detail and the very tight specs. That being said I prefer it more.
That's my opinion from the outside looking in. Now from the opinion of someone who quite a bit of dual given, but does not hold an MEI.... I wish I didn't have to take a checkride for the MEI... and I'm dragging my feet on it too