I don't consider it a replacement for a full size axe, but it does do a good job where a hatchet may have been the ususal choice.
I look a the khukuri as being a multi-tool.
It does the job as a wood chopper/splitter, as a draw knife, as a regular sharp blade, and a light hammer. A hatchet really excels at being a woodchopper/splitter and hammer, but comes up a bit short in the other categories.
The weight to function ratio, in my books, puts the khuk ahead of the hatchet.
Picture this: you are in the woods and must construct a shelter, dig a fire pit, dress your catch, carve your wood, do normal cutting chores, process kindling, split firewood, trim braches, modify gear and you are only allowed to carry one tool. (you can also have the gear to sharpen your tool if it gets dull)
Would you pick the khukuri with its long blade or would you want the hatchet with its short blade?
Plus I get to tell people I have a hand forged HI khukuri from Nepal, instead of a hatchet from the local hardware store.