Too bad you couldn't save the plaster, bubt I suspect you needed good access to uncover all the scary stuff previous owners did. At some point I can see how compeltely gutting it makes sense. Grat job restoring the trim, molding and panels... and floors. Its' still has it's character. A wall is still just a wall, but all the trim and small touches give it character.
I love how heavy those timbers and floor joists are.
Just a note, but the ceiling lathe may have been acting to tighten things up. It creates a semi boxed structure. Although with joists that thick and the subfloor above it, it shouldn't matter much. Drywall has no real strenght, so if the joists move at all, the drywall will crack.... where as the lathe may have tightened things up.
Previous home - 1968 single story Ranch/Colonial, 1200sqft - 11 windows
Current home - 1925 2 story Beaux Arts Neo-classical overlooking the Mississippi River, 3200sqft - 48 Windows