Don't understand this what so ever.
First if you already have an XB1 - why would you get a disc less one?
Why would you have a pile of physical games if you don't already have an XB1?
The xb1's that cost $300 usually come with a game. So will the $200 ones come with a game?
Plus you can easily wait for a discount on the XB1, and XB1s for them to drop to $200 or lower.
So what do you gain by giving up an option of using discs?
You don't gain anything. You lose UHB Bluray capability. MS earns a new only digital customer though, unable to sell your used games of course.
The X1S will also get a revision btw, so in the end the difference will likely be 50 dollars, not 100.