Doubt that a 1.5s cast kills the comp to box. Nor will it be a valid enough reason to favor haste over mastery with the current haste values.

cast time / % haste / haste rating
1.4s/ 7.1% / 914
1.3s/15.4%/1969
1.2s/25%/3200
1.1s/36.4%/4654
1.0s/50%/6400

Not saying mastery > haste in 4.2, but the hungering cold nerf alone will not be reason enough I guess.

Besides, it was a much needed nerf for retardedly OP frost dk's.