It might seem like Admiral wank but I think there is more to these admirals being able to withstand/dodge haki attacks. I mean we have that panel of Akainu getting hit with Haki attacks and he says that haki users are annoying. I think when we get to Logia awakenings we will see why they are so powerful. We are mostly relating to Katakuri and his FS when there actually might be more to it.
Aokiji and Kizaru's panels might be attributed to FS but I think Akainu's is different. He felt those attacks, he knew they were haki coated, so either he is just too damn tanky and it bothers him a little or they have a sort of permanent CoA which saves them from injury like BM has or Logia awakening leads to being able to completely become the element and as such you become sort of the terminator type thing (the one in Terminator 2, the liquid guy) where even if you get cut with haki it still cannot damage you as much or does not damage at all.