Seller to apply 10k credit to closing instead of reducing price

[Eric S.]

I am currently in contract for 2 unit at 300k with 4k closing costs. . Each unit rents out for $1550 currently. Taxes are $3300 a year. Everything is good appraisal came back good. Only thing we are going back and forth was remedy of items that came up during the inspection report. We finally agreed that 10k was good number. Was personally less than I wanted, but since I already have leases signed for 2016-2017 school year at 2k a piece, I just wanted to get the deal done. 

Usually when I have done deals the seller just reduces the cost of the property in this case by 10k, but instead I am getting a credit towards what I need to bring which is 15%. This great because I can keep more cash in my pocket. Also it was mentioned that I could do POC and get check outside of closing, but don't want do that becasue of tax implications. When I talked to my bank (smaller local investor friendly bank that writes their own guidelines) they had no problem with this.

My questions is 

1) Why would the seller choose this? Is it keep the sell amount as high as possible/

2) I don't quite understand how this is possible. I have been ensured that it is by multiple people. Bank, Title, Realtor, but still don't have a clear explanation so leads me to be a little hesitant as I don't clearly understand how this works exactly and the motivation why the seller wants it this way.

3) If this is legit. I would want structure more deals like this if I am financing. Instead of reducing the price receive the credit towards what I need to bring to the table. 

Thanks for everyones help.

Cheers!