Earlier this summer I deviated from my regular beer, Narragansett, to sample some others. At one point my refrigerator contained Founders All Day IPA, Harpoon's new Take 5, and some Magic Hat that had been brought to the house by guests. Whenever I drank one I'd think, I wish this was 16 ounces instead of 12.
The primary reason for this is that I drink a beer with my dinner, and the larger-size serving works much better as a meal accompaniment. Even with judicious sipping, too often I get to the end of a 12-ounce beer with several bites of food remaining. Draft beer is usually served as a pint, and I think that's probably related to food as well, at least a little.
I don't know who first thought of the 16-ounce can (I suspect that has been lost to beer history), but that person's effort is certainly welcomed by me.