Better aesthetics and even 18% reduction in file sizes refuses to move the sleepy elephant (h265 is likely still fringe stage). Even a trivial codec licensing fee of $2.50 for Pi users was not very successful for many media formats (i.e. 10% of retail price kills most of the market). However, h264 support was important enough to wrap into the pi4 retail price, and even at 11m/pcs a month there is still no stock available.
https://www.youtube.com/watch?v=ygU2bCx2Z3g