1) Even with the damage out of whack as frost right now, I honestly prefer pvp as frost simply due to endless winter. Having chains of ice apply frost fever helps tremendously with pvp rotations as a whole. As either blood or unholy, I have to basically go through a whole extra rotation before I can even think about using a 1F1U rune ability. This also makes death strike annoying to use as any spec other than frost (even where it's less effective), simply because I have to do chains > plague > icy touch > blood runes > wait for 3rd frost rune to come back > death strike. It just doesn't flow very smoothly. This is, of course, assuming that all of my diseases stick on the target. This is also another reason why I wish death strike simply gave 100% healing done, and 50% extra per diseases. (rather than none + 100% per disease). Death strike is another of those abilities that I think would do well to have less disease dependencies.
2) This leads me to this point, because of that situation, having to use 3 frost runes per rotation in pvp really messes up my rotations in pvp as essentially any spec wanting to "finish" with a 1F1U strike. This is because chains of ice doesn't apply frost fever at the core level. If this one change was made, I'd be a lot more comfortable pvping on the dk, and it would feel infinitely "smoother" to play.
3) If Icy touch damage is going to stay low as it is, I see no reason to not have chains of ice be our "go to" frost fever application spell for rotations. This one change alone could be made without breaking the overall rotation philosophy. It would also lend itself well to tanks that need to snare a mob (forfeiting icy touch that rotation), without forcing them to screw up their rotations.
4) The chillblains > endless winter talent feels bloated as is already anyway. I feel like I have to basically spend 5 extra talent points in the frost tree if I'm going frost spec if I want to pvp without it being a headache. That's not fun, because I feel cheated out of cool other talents because I feel compelled to pick up something that mechanically feels mandatory. I think you could do well to make chillblains 2/2 for 15/30%, and roll endless winter in with it to make mind freeze cost 10/20 RP less. That would feel much better speccing into.
Just some thoughts. :)