No, it is not the standard, nor is it as good a method as any.
Energy, without a whole lot of other data, says nothing dependable about what a projectile does to tissue. For a known projectile, velocity is more useful.
To illustrate.
A 200 pound great white ape on meth is coming after you/your family inside a house, put in order of preference which firearm projectiles you want to be throwing out of the below list. To keep it sporty, you are stuck with a single shot.
A. 117 ft.lbs
B. 129 ft.lbs
C. 343 ft.lbs
D. 1256 ft.lbs
E. 444 ft.lbs
What do those numbers tell you about lethality?