Firefox gstreamer1-plugin-lame problem

[scratch65535 at att.net]

As a prelude to installing the  VLC package that turned out to be
broken, pkg removed Firefox 47 (it didn't explain why).

Since there doesn't seem to be any way to revert the removal, I
tried to install FF52 as a replacement.  That failed with a
complaint that the gstreamer-plugin is missing its "lame"
dependency (lame is presumably a name rather than a judgement).

Why doesn't pkg RENAME the bits that are meant to be removed, and
actually remove them only after getting post-install permission?
Then they could be reverted if the install fails, as the VLC
install did.