Expack3 is a staff member, as can be seen on https://www.pcgamingwiki.com/wiki/PCGamingWiki:Staff
In regards to the Essential improvements section, per the Editing Guide, it's meant for, well, "essential" improvements that we can assume is of a noteworthy addition to most players:
Other non-essential mods goes below the Other information section:
The gist of Expack3's undo's is that the mod, while of interest to some players, isn't seen as being relevant or "essential" to most players due to it ultimately being just a content unlocker for content meant to be unlocked through regular play. Like it or not but the developers have consciously locked the levels behind difficulty levels for one reason or another, and a mod that bypasses said restriction isn't essential just because a few players disagrees with that design decision. And so, the mod -- the content unlocker -- isn't essential either as a result. It's a nice mod for some users that cares about it, and deserves listing, but not "essential" enough to be included under the "Essential improvements" section at the top.