I work with investors and am always amazed on the different streams of properties that they receive.

In the least bias way possible....a Mortgage company's business model is solely focused on mortgages, whereas depository institutions (like Chase) have many other income streams and priorities. 

The expense for just that will be somewhere around 30-50k (engineers, water crossing permits for the stream, excavation, old tank removal, more permits, etc.).

Plus, with so many recreational activities around here, there's always sure to be demand for vacation rentals and other services which can give you a steady stream of income.

Then next year 2017 we will report the house sold in 2016 and start the fun task of adding another income stream to our tax reporting?  

No joke I have a way of legally getting paid on mortgages now along with the other multiple income streams associated with being an agent its  a great industry to be in.  

Buy them, there is still an increase profit stream in front of them, versus other mature industries.Little Guy strategy- same as the big guys.

Is there another reason why seller could benefit from a series of regular payments (i.e. annuity-like stream) rather than from a lump sum payment? 

We looked at multiple places and I didn't really think of this as a stream for "passive income".

If you used a state sponsored contract it will be spilled out in writing.