Happened to spot this on the last posts display, figured I'd clear a couple of thing up.
The bug, as you point out, was never fixed. Dropped weapons don't ever clean up and contribute to bloating up the size of the save game.
However, the unofficial patches for PC did NOT actually fix the bug. We used a workaround for it instead by setting the chance to drop variable to 0 so that NPCs never drop their weapons even if visually it looks like they have.
The only way this can properly be fixed is in the engine code and none of us are getting another official content update from Bethesda.
It would be nice but Skyrim is Finished. Also I think Bethesda has to pay for patches on consoles. Quite often making a patch fixes some bugs but others have a habit of showing up which can be even worse than the current ones.