I have just read a thread in mob wars reference elite and optimal items being worthless when opened at certain levels. I have found this to. I am level 4150. And i was thinking how about as you move up the levels at a certain level points the elite and optimal items attack and defence go up. This could be from the first elite, optimal you craft .
I'll suggest this should be done from Miami onwards because they have achievement for defeating a level 50 hence players keep opening them till level 50 getting the random drops in the process. I don't see the need for the lower cities