If I were to name the greatest failing of 5e is that it was pretty much playtested and designed with the assumption of variant rules to modify the base experience and no only did very few of those rules come, it moved forward as if some of those variant rues were base and if future variant rules would not to be added.This is what they were supposed to do when 5e was playtesting but once it came out the "crunchy" options never really developed.
Like there could and should have been official rules for Herioc, Mythical. Cinematic, Gritty, or Wuxia combat that used WOTC's resources and the large community base for playtesting.