"Chances are" was used for a reason I never meant to imply that it was always the case.

I recently snookered myself by assigning Mental Shields to Venus: It wasn't obvious if the feat could be ignored to allow two-target Mind Control (of a pair of scrubs under 100 points), but working from the "negative effects aren't optional" theory I played it as if it was not optional.

This one seems somewhat borderline, because like Nova Blast it seems as if the "benefit" (not taking feedback) is contingent on a couple of specific choices (mind control a 100+ point figure, mind control only one other figure).

You can choose to not use Mental Shields in order to MC multiple figures.

The ones which aren't optional are actually listed as such in the PG.