Tina requires fundamentals to approach your opponent without getting bopped. She got those T-rex arms. And players dont like using characters with T-rex arms.
Considering the fact that she has 66k, a grab that does 40% on HiC, and arguably the best stun game in the game, I'd have to beg to differ. Also, her wall game is godlike as well.
Generally when people were on the Helena/Christie/Rachel train. Her inability to steamroll opponents in the same manner led to people seeking out alternative options, thus giving the impression that she's in some way "bad". Also @Doa_Eater thinks she's worse than dirt.
She got a few nerfs going from 5 Vanilla to 5 Ultimate