Your point is moot as Ubers could drop anywhere a normal unique could starting at level 85.
As of season 4, they now start dropping at level 55 and have an increased chance of dropping from the ladder bosses (though Duriel and Andariel have the highest chance).
Also Ubers were always meant to be a “fun to have, not mandatory for your build” type of item. If you ever felt you needed it to make your build work then there is something wrong with your build.