[Q] What is this "material change" that is relevant to I-829 approval that people are talking about?
This new concept was first referred in the Neufeld Guidance Memo of December 2009. Basically, USCIS has left the term to the "when we see it, we will know it" standard. Obviously, this will not work. Logically, one cannot say something is "material", without first asking "in respect to which requirement"? Obviously, the requirements here are the specific I-829 requirements stated in the regulations.
The strange thing is why did USCIS feel the need to bring in this new concept, because either you meet the specific I-829 requirement or you don't.
USCIS is legally wrong to bring the Matter of Izumii case to aid their argument, as this case is completely inapplicable to I-829 situation.
USCIS is also legally wrong to say that this concept existed in the past. However, that's what USCIS is saying. And until USCIS changes its policy (of which there is some chance as USCIS specifically asked for comments on the Neufeld Memo) or there is a court decision stating so, the concept of "material change" will impact I-829 petitions. It's just an unfortunate situation of USCIS missing the ball and muddying the water.
The bottom line is you either met the specific I-829 requirements or you don't. Why does USCIS need to bring in the "material change" concept? You only bring in a new concept when you have no legal basis to deny. That's why.