Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Because the 10hr battery life has been their target goal. They put in enough battery to meet the goal. Personally, I wish they’d set a higher goal. The 12mini sounds nice, but its big win on size is the reduced height and depth - they could have those, and make the phone 2mm thicker and put in more battery, and it’d make for a nicer experience.

What do you mean they put enough battery to meet their goal? My Air 2 is surely slimmer than my original ipad but still gets the 10hr battery life, also has more RAM.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.