They charge much faster now, which is good for sales because a battery that charges fast is very convenient. So it progressed.
Fast charging degrades the battery slightly faster than slow charging but it's not the end of the world in my opinion. I'm guessing it's much better to not keep your phone battery at a high state of charge for a long time, much of the chemical reactions that degrade the battery happens at high state of charge, than avoiding to fast charge it to 80%.
EDIT: Huh, I looked it up and I'm completely wrong. Battery sizes haven't changed.