Well that is a good question I suppose.  I think there might be several answers to this.  I will go out on a limb and give me two cents worth.

1] The number of instructors that want to get better at this are so small that the event would not likely work.  The National Flight Instructor Conference lasted I think two years maybe three and not many people ever heard of it.  

The age old problem is that the most active CFI's are on the way to another job, the other set of active CFI's (like you) could teach the course.

2] Some of the instructors I know think they already know it all  

3] Many of the CFI's who care have full-time jobs and could not make a program that is held out of town, for that matter the ones that teach full-time can not afford to get off work or even travell to the event.

Sorry I am so negative on this.

The only thing I could think of would be a computer based type course, such as the Gleim CFI FIRC - That was very well done and we could take it at home.

When I was in San Diego with 1700 CFI's in the San Diego and Imperial County only 50 out of those CFI's showed up for the 10 week flight instructor workshop...then when the FSDO stopped renewing the CFI for attendance only 15 showed up.