I am acquainted with some of the writers/contributors/editors and they did try to improve it as they developed new units, but there's a fair amount of unevenness across the years of material. This was not due to the people working on it. In my opinion, this was due to some flaws in their concept of development.
Imagine how amazing PowerXpress would have been (and could still be) had they taken our Rotation.org model of "cloud" writing/sharing, and put Powerxpress ONLINE for people to talk about it and improve it.
When will the denominational publishers figure this out?