The GPU difference is not minimal. 18 to 12 cores is a 50% boost. Why is it that developers struggle to achieve 1080p/60fps on XBox One, but have no problems on PS4? Also indie developers feel scorned by MS.
Yes they are bad at hardware design. What the chassis design proves is MS has no clue how to keep the unit cool except by throwing lots of empty space and huge fan at the problem. Sony magically keeps it cool in 50% less space. Sony hardware engineers are just better.