Enigma was one of the most interesting additions to Diablo 2 in its long lifetime. The item-only skill model was simply awesome, but it brought a little too much to the table for the superwealthy willing and able to acquire one. If they executed it better, but still kept it interesting, they should have even more item-only skills in D3.
I agree, it really changed the whole game. IMO, it was far too unbalanced,like you said. They should have made the rest of the mods, besides teleport, crap. That would have been more balanced.
I hope they get away from 1-2 items always being the best for a certain equipment type.