The bridge set for "Generations" was modified from the standard set used for the TV show. There was no time to tear-down and rebuild, since they basically finished "All Good Things" one week, and started filming "Generations" the next week... As far as the DS9 sets not being detailed enought...
Rob - I am not sure of Avery Brooks has a desire to reprise Captain Sisko. And I also think that Rene is also not likely to return. Additionally, when production ended on DS9, most of the sets were destroyed, not stored. That would mean a huge cost outlay to re-build. As much as I love...