I have to say, I hate it when I'm mopping or repairing something and an NPC walks straight through and gets hurt. I feel like they should just keep walking and not interrupt the process.
The issue is mainly with puddles since the NPC's all share the same pathfinding, they constantly walk through puddles while I'm cleaning them. Then they get hit by me mopping, and it hurts my ratings. I am pretty certain a quarter to half of my "Got Hurt" ratings are because of this specifically. But more importantly its incredibly frustrating with how often it happens; it makes me want to stop playing the game.
On top of this, I think an idea for a cool upgrade could be having a wet floor sign appear while mopping so NPC's walk around the puddle and won't slip while you are cleaning
Example: I was mopping this puddle and these two got knocked down by walking through while I was mopping