Isn't 1(mc) redundant?
 

It's like kicking that poor card when it's already down. I've always thought the qualifiers meant "This card would receive an 8 if it weren't for this terrible centering", thus 8(oc).

probably but they are just trying to be consistent with the nomenclature they use for all of the other number grades.

In PSA set registry weightings, the 1MC will get the same weight as a regular PSA 1; you can't get less than a PSA 1 (except Authentic, which I believe counts as 0.5 in the weightings).