I'm going to just have to agree to disagree. I do not believe an ilvl incentive is necessary.
I will openly admit that I am biased as well. I've always felt that my critical comment towards the "it's too easy!" crowd is the fact that the vast majority of those players haven't even attempted to try to challenge themselves. Like you've said in your previous post, min-sync A4S or A8S, doing A4S with Nisi, heck even do A8S and not sacrificing Water. Even A8S with current gear scores and echo presents a pretty stark challenge compared to A12S with the same gear.
I think for me the biggest issue with giving an ilvl incentive is that suddenly there will be a group of players who feel entitled to attain that boost, even if the intent of the content was to crush you over a million times before you can beat it. It'll lead to, for the lack of a better word, whining.
I do believe part of this issue is the fact that there isn't enough content. I feel we both agree that there needs to be more content overall that is appealing to both the midcore and to elite players alike (note not elitist players) and the fact that YoshiP is contemplating this "next level of challenge" is a good thing for the game's health. You can't have super hard content as it'll alienate the midcore and you can't have above average content as it'll alienate the elite players so it'll be good to have the two different levels of content available and should placate many of the "too easy!" or "too hard!" comments.
I'll also expand on my thoughts about why I do not believe ilvl reward is important as it stems from my own perception on how they should do this challenging content. The content should be designed with min ilvl forced on, thus it becomes a matter of player skill to clear the content and not player gear. ilvl rewards mean nothing to this content and thus no need to be rewarded either. However, rewarding ilvl boosts would encourage what I stated in my third paragraph of this post - more whining. Perhaps that won't happen, and perhaps I'm being too critical of the overall population, but that is my thoughts behind it.
Time will tell what will happen because in the end, all these posts are our personal opinions for the Dev team to read and for others to provide additional input or disagreements too.