Doc, noone is advocating saddling the last tenant with the responsibility for all the wear and tear the floor saw over the years. If it was 80% worn out when this tenant moved in, and now is 100% worn out... then yes, it's a wear and tear thing. If the floor was 3% worn when the tenant moved in, and is now damaged to the point of requiring replacement... then, in my mind, the tenant IS responsible for a good portion of it. Maybe 100% of repair costs, or 85% of replacement costs.
For example, I rent rooms out to two tenants. One tenant has lived in a room for two years. I do semi-annual inspections to make sure nothing's going wrong, check weatherstripping, etc. There are minor scratches and dings in the floor. This is wear and tear, and he'll get his deposit back. (Except for the $50 for a drunken friend punching a hole in my drywall and refusing to pay to repair it.)
I had another tenant. He's been in the room 6 months. When he left, there was gouges and dents in the floor from dropping things all the time. The rental agreement spells out that ALL chairs shall either be on a rug, OR shall have (provided by me) pads on the feet. He chose to remove the rug I gave him, and proceeded to grind a 1/8" deep groove in the floor where he slid his chair back and forth from his PC. that is NOT reasonable wear and tear. It cost me nearly $500 to repair all of this.That amount came out of his deposit. He took me to court and lost, so the court agreed as well.
Point is, I see my rental rooms as a business, and set aside about ~15% for repairs and contributions to the maintenance fund, but tenants can and DO damage houses beyond reasonable wear and tear.