Unfortunately, my pipes have a slight leak but had they disconnected the hoses like they should have we would have no issue. 

There are tons of cabins in Gatlinburg with pools that are in the basement, in many cases right next to a game room or living area and bedroom, so obviously it doesn't have to be disconnected. 

Its a pain to connect and disconnect, and you risk damaging the faucet if you're not careful.

I can tell this has been rambling and disconnected.

If the heater is supposed to no longer be in service, then the gas line to that device should be disconnected and capped; just putting a shut-off valve in will allow somebody to turn the gas back on. 

Tenant agrees to notify Landlord in a timely manner of drain stoppages that they are unable to clear themselves.2.DRAIN CLEANING PRODUCTS.Tenant agrees not to use caustic drain cleaning chemicals in any of the drains or plumbing fixtures.Such products may cause damage to the plumbing system and may be hazardous to the environment.Tenant may be able to keep drains clean and clear with regular maintenance by pouring down the drain a quarter cup of baking soda followed by a half cup of vinegar.If there is a minor clog in the p-trap (the curved portion) of the pipe under the sink, Tenant may disconnect the pipe, clear the pipe manually, and reconnect the pipe to clear the clog or may call Landlord for assistance.

They didn't get the SS because they didn't have a wrench to disconnect the gas stove.

I would probably piggy back some on Peter's idea and cite the lack of basic building knowledge some tenants have,  with interesting examples like....pulling out a dryer to get a lost quarter but disconnecting the vent inside the wall to then vent moist air into the framing causing expensive (thousands) rot repair.putting a tarp on junk (literally) but slanting the tarp angle right into the siding in rainy season (rotting your new siding--but preserving their worn out tires).attachments to clutter, rusty junk, semi-operational cars and illogical desire to retain said junk and debris.I sort of also fall back on the divide between some of the personal management skills of landlords and tenants (realizing it may be why they are tenants, for example). 

@Rich Hupper most commercial properties are purchased with leverage; so, cap rate and CoC return are disconnected.

This also avoids disconnect and reconnect fees each time a unit is turned over.