Why don't the wildcards have to roll?

I get that they can copy the chosen TA, even if the character with that TA can no longer use it themselves, and used that very trick in my last AvX tourney, but it doesn't say that the effect is limited to characters currently using the TA.

It's pointless for a character to roll if they neither have the TA nor the ability to copy the TA (if you choose mystics, my Avenger can't use mystics... That wouldn't be news), but if my wildcard is out there, why wouldn't they roll?

Any character that can use that team ability (a wildcard can use the ability, even if they aren't at that time) can't use that team ability for the rest of the game (which would preventt he wildcard from using it later on).

Only characters that can use the TA at the specific time Scarlet Witch uses No More Mutants have to roll for the effect. Characters that have the potential to use the chosen TA, but aren't actually able to use it at the time her effect is activated do not have to roll.

Another thing people miss a lot with Power Cosmic and the fact that it only protects powers from being countered is that it doesn't protect combat abilities. I've caused several players fits with a timely countering of their flight, carry, etc. when they just assumed they were safe.