I wouldn't think for a second that it was oversight. They have to differentiate the products else why bother selling both, if the book was just an SP4 with a keyboard dock (my personal opinion is they shouldn't sell both, but there should be the SP4, and then various accessories so you can use it as you like, either as a surface pro, or as a surface book etc)I was 100% going to buy the surface book when I first heard of it, thinking it was essentially a surface pro 4 with a dock. The battery situation and lack of stand (which is such an oversight, that thing is amazing) made me choose the SP4.
Its these type of issues that give SP4 a quality hit. There are several issues that MS needs to address ASAP....The maddening graphics issue on both devices -- that the Windows 10 built-in Maps app shows NO ROADS IN ROADS VIEW -- has been solved on the SB but NOT the SP4.
Microsoft and Nvidia (graphics card on SB) have integrated a solution in mid-November. After 35 days since both devices launched, MS Engineer Rohan Thakkar, posted a solution.
But for the SP4 -- the issue since launch (Oct 26, 2015) is now 60 days old -- there is no solution. Both Microsoft and Intel (graphics card on SP4) say they are working on a solution. Unlike the Nvidia graphics card which is custom designed for the SB, the Intel Integrated HD graphics 5## on the SP4 is part of many other computer devices. This graphics issue affects more people, which could give hope for a possible solution, but 60 days of an issue, indicates more of a technical hurdle than possibly the business model will allow.