Being asked to "adjust" job description

I'd like some feedback from those much more in the know on these kinds of things please....

There are four of us in my department (and all in the regions) with an identical job description (AS02) and we are being asked by HR to update it. We are being told it is because our current one is "outdated and too long at 14 pages, because a normal job description is typically about 5-7 pages".

They want us to remove items that no longer required of us and add ones that are missing. Once we complete the task, HR will supposedly "access some similar job descriptions from other departments to see which may best reflect the duties performed by these positions, but they need an updated list to proceed".

Italicized quotes are from manager's email.

Years ago, after fighting tooth and nail internally to have something done, we threatened to file a group grievance over our positions being under classified. They immediately brought in an outside classification officer and made sure that our descriptions didn't require a level up, to the point of removing from our daily tasks the duties that would have meant reclassification. They then tried to take the position that we were now in fact over-classified and should actually be AS01 but by their good graces would leave things as is.

The higher ups involved in that terribly stressful time are all long gone. However, there are those new to the department that I trust much, much less further than I can throw them.

I'm very willing to hear from this group that the terrible feelings we all still feel are clouding the present situation, and that we should go ahead with what is being asked of us. I've been in the PS and this department long enough though that this present request has a very bad stink to it.