Please forgive the delay in my response to your post of July 15.
MES strips out much of the historical development of and philosophical ground for economic thought that Mises includes in HA. MES sticks mainly to economic theory and policy and gives a more elaborate development of economics theory and policy than does HA.
I would not say that it is essential to read HA to have a good grasp of AE. But, it is essential to read HA to understand the historical and philosophical context of AE.
I suggest you look at Bob Murphy’s Study Guides to MES and HA to better compare and contrast them.
https://mises.org/library/study-guide-man-economy-and-state
https://mises.org/library/study-guide-human-action-treatise-economics
