My 3100mAh Galaxy Note II has 4G, and the battery life is noticeably worse than my old 1200mAh iPhone 3G.
Battery tech has long been one of the biggest limiting factors in mobile tech, and I'm not quite sure that advances in energy density are moving as quickly as everything else. Which means I think that batteries are slowly lasting less long as energy usage of new features consistently outstrips improvements in the tech.
Remember when phones used to last a week or a month? Now we're lucky to get a day, day and a half.
They will innovate.