This may be why the rarity of the 20-21 items. There are the most of those that are artifacts because they were made before we went to lvl 40 cap. There is a rarity of 21-40 named artifacts. Which is probably why the unique artifact generater was put in. If I can figure out the script that grabs the premade artifacts maybe I can tweak it... or add some more 21+ stuff.
I like random artifacts. It give the game that diablo feel of not farming a boss and just getting lucky.