For RFI usage, I'll just zoom in as I like to the appropriate area, and print to an 8.5x11 PDF using the Visible Portion of Current Window and Fit to Page options. I never re-scale anything for that purpose.
Yeah, that would be a nice feature I guess. But I'm not Autodesk and so I can't answer why they would remove it.
I wouldn't do what you ask anyway, myself. I don't think the model file is the proper place to keep post-contract, administrative documentation such as RFIs and COs and such.
It would be nice to shrink or expand a particular view to fit a particular Revit Sheet without actually changing it's official Scale...just a percent-zoom feature or something. But even so I wouldn't care about keeping it in the model. Revit isn't anywhere close to being a full project management solution on its own, and I wouldn't attempt to use it as such or even attempt any of those requirements within it.