It's the path of least resistance and how they and their clients are compensated.  

I would go with a hail resistant 30 shingle then you get a discount from the insurance company .

Haven’t discussed pricing yet but probably won’t get as great of a deal on this one but it is a beautiful log cabin with big windows and fireplace overlooking the water.

Both houses have so-called 3-tab shingles that have low wind resistance.

The HVAC and water heater estimated to be 6 to 8 years old by the inspector.

I do not unless it is an emergency so the pipe bursting recently was flooding their home and unfortunately they didnt know how to turn the water off regardless that I told them how before etc! 

I can tell you these facts:SFH lots of times do not qualify for max cash out options b/c the rent can'y support the max loan payment.2 - 4 unit houses always have a 1.5+ DSCR and never have a problem affording the max cashout...STR rental structures blow LTR rental structures out of the water. 

It includes high-efficiency HVAC systems, contemporary LED light fixtures and multiple tankless water heaters.

If I was the tenant that got damage from another tenant's water heater, I would expect him to pay the bill.If it was a pipe in the building and not in their unit, then I would think the landlord would be responsible.

I already owned a home not on the water.