Two things. It patently isnt "Utterly useless" or thousands of drummers would not use one. If you can get the sound you like tuning by ear, then great, but dont knock others for how they get the sound they want.The Drum Dial is an utterly useless device to tune drums with. To actually tune with it would mean that an equal tension reading at each lug equates to the same pitch at each lug and this simply isn't the case. If you need help tuning, get a Tunebot. Otherwise, keep practicing until you can tune by ear. The Drum Dial's only use is to tell you what tension a head is at for future reference once you have your drums where you like them.
Secondly, If the tension on the head is the same at each lug and your drum has not got the same pitch at each lug, then either your head is shot, the bearing edge is poor or the hoop is not flat. Not the fault of the DD.