Games are often designed around a 90-100ppi screen density rather than a specific screen size and many older games (that are more likely to be run on 15w APU's) UI's don't scale well above 100ppi. That's why non-scaling UI's still look just right on 15.6" 768p laptops, 24" 1080p & 32" 1440p monitors. You can get away with stretching it a bit to say 110ppi (1440p @ 27") but trying to play such games with non-scaling UI's on a 1080p @ 7" (314ppi) is like buying a 14" 4K monitor and trying to use it at 100% scaling. No matter how ultra, ultra, ultra, ultra, sharp things may be, UI elements in many games will shrink to the point of becoming unusably small, as has been seen previously with 7" "Windows Phone" tablets.
Dropping down from 40-50fps (720p) to 18-30fps (1080p)
that you'll typically get on 15w APU's even for 6 year old games along with a plummeting in battery life is not a good trade-off for extra sharpness. Too high a resolution on too small a screen just means they both run new AAA's badly due to performance and simultaneously run older ones poorly due to non-scaling UI's. So 720p overall is actually quite right for the screen size. People just need to step out of the
"but mah moe-bye-ul fone is 65,536k 9000ppi" mindless marketing rat-race and understand the obvious Usability / Performance / Quality 3-way tradeoff a little better, along with the fact many thousands of Windows games are definitely not coded like iOS / Android apps.