Your suggested "idea/range of ilvl numbers" is horrible. Sure it makes the raiders happy BUT look at it.

In the entire expansion, nonraiders would only go up 20 iLvls. That's over a year's worth of content, and non raiders would not "feel" any stronger than before.

It also means all the nonraid content would be
1. Of 0 interest to raiders.

2. Even more faceroll than it is now. If every patch you're only going up at most 5 iLvls, the difficulty will not see any noticeable change.

That would literally be catering to the 1%.