Now that her shield explosion is removed, all her abilities completely lack uniqueness and look like very close variations to skills already in the game. It's a shame really, she would have really benefited from a class update.
Riot has already said that it's because Karma is a support-mage instead of just the generic 'mage'.
There are a bunch of mages in the game that are just generic mages and they kind of stomp all over each other's feet to find a reason to be picked.
And given that mid lane Karma is at least one player's pocket pick in the LCS, She can't be that far off the mark.
She's a support.
