Why are laptop vendors avoiding the Iris GPU? The previous generation XPS 13 had the IRIS gpu and if you skipped the high resolution touch screen the battery l

Why are laptop vendors avoiding the Iris GPU? The previous generation XPS 13 had the IRIS gpu and if you skipped the high resolution touch screen the battery life went from a pretty good 12 hours to an amazing 20 hours. Did I mention I had touch screens? Dell also has an annoying habit of restricting the NICE cpu and 16GB ram to the high res touch screen. Seems really weird to spec such a nice laptop with the HD 620 graphics when $20 or so would get you the iris (with an on chip frame buffer) 640 which approximately doubles the performance. Same TDP even.