The overall slowing capability nerfs were long overdue imho. I think the end result it's a tad drastic, i would have preferred a bigger reduction on Frostbolt (from 15 secs to 5, instead of 8) and maybe a bit smaller one on Blizzard (1.5 seconds means that as soon as they walk out of the spell's area they are basically at 100% speed after a single global, would have preferred at least enough time to recast it while still counting on the impaired movement).
I am not that much worried about the damage part: they just offset the change with the amount they felt was enough, more tuning will be coming if it will end up being needed.