The Talmudic text debates what categories these fall into. Is plaiting the hair “weaving”? Is it “building”? (note this sweet midrash: And the Lord God builded the rib [… into a woman]: (Gen. 2:22) this teaches that the Holy One, blessed be He, plaited Eve['s hair] and brought her to Adam, for in the sea-towns plaiting is called 'building'. )
But a story of told of one rabbi who didn’t bother trying to fit things into categories.
R. Nahman b. Guria visited Nehardea. He was asked. If one milks, on what score is he culpable? On the score of milking, He replied. If one sets milk, or what score is he culpable? On the score of setting milk, he replied. If one makes cheese, on what score is he liable? On account of making cheese, he replied.
In other words, R. Nahman’s responds to the people – “just because.” That does not fly. And the people knew it:
"Your teacher must have been a reed-cutter in a marsh," they jeered at him.
R. Nahman goes back to the study hall and gets the answers (milking is like “unloading”, setting milk is like “selecting”). The people were right not to accept high-handed answer.
The result is not the point, the process is. And it is not arbitrary. There has to be a logical reason for a law, particularly a restriction – ultimately backed by text.
The answer is never: “Just because.”