The struggle, of course, comes between the philosophy of Blizzard and the immediate distaste of the player base for nerfs. One argument I've seen used by players is that death knight representation is actually rather low in PvP. I've seen quotes that top arena teams have death knight representation as low as 7% in the 3v3 arena bracket.
Of course, that argument gets a little less solid when you understand that with 11 classes in game, 7% is only about 2% away from an "equal" slice of the pie. In addition, Blizzard needs to consider all arena teams, not just the top few.
It's also worth noting that more than balance, this change seems tailored to a certain philosophy. Hybrid healers of all stripes will be receiving a PvP healing nerf (in that PvP Power will no longer affect their healing), so in that case, this type of healing nerf falls into line with that. It helps healers feel like they have a place in PvP, and no-one likes dealing with an immortal solo character who can also do amazing damage on you. If Smite was a top level damage dealing spell when used by holy priests, you'd expect that to be nerfed too. Is this enough justification? Perhaps not, but it is the justification Blizzard's using, and it passes the smell test in basic logic.
If we are to counter this, I believe our best philosophical argument is to note that Death Strike is more than a "self-heal," it's the cornerstone of how a death knight tank works. We are, by definition, a self-healing tank class. In this case, healing isn't nerfing a "hybrid" ability for us, it's nerfing a very definite cornerstone of the way our tank spec works, similar to say, nerfing Savage Defense for guardian druids. To say that our self-heals are too high is like saying "Shield Block blocks too much damage." Of course, that phrase can be true too, but one gets the feeling Blizzard is looking at this as a healing power problem and not as a tank takes too little damage problem. If we can prove that the latter isn't true, and that blood death knight survivability is too low in PvP, we might have a better chance of getting them to reverse this.
The final option is that Blizzard just plain prefers that tank classes should focus on DPS specs in PvP and shouldn't count on their amazing defensive abilities against NPCs to translate over to fellow players. In that case, it may be the argument isn't worth having at all, and we should all work on the perfect frost PvP setup.
Still, as a player whose first love is the PvE side of the game, one thing I will say is this: If Blizzard must nerf the class for PvP, please, please, please make more changes like this. Death Knights, as with many other classes, know the sting of having good PvE spells nerfed or removed for PvP balance purposes. Reducing a skill's PvP effectiveness without doing the same in PvE should very much be the target, and whether Death Strike should have been nerfed in PvP or not, this was about the most perfect way to do it from a PvE tank's perspective.
Crush the opposite faction, win fabulous prizes
There's 2 new daily quest factions going in with this patch, one for the Alliance, and one for the Horde. Once you do a quick quest to unlock the hub in Karasang, you'll get the chance to grab some reputation gear from your side's vendor. A level 458 trinket awaits you immediately. On the Alliance side, you'll grab either Knightly Badge of the Shieldwall or Durable Badge of the Shieldwall. Horde will get Dominator's Knightly Badge or Dominator's Durable Badge. In all cases, the trinkets will cost you a bit over 100 gold each with guild perks. If nothing else, these will be a nice quick and easy way to help young death knights get to heroic dungeon running item levels sooner.
Unfortunately, that's the last pure gold reward you get, as all subsequent rewards go back to the new paradigm of requiring valor points to purchase. At Honored, you will be able to pick up Circle of the Shieldwall or Seal of the Shieldwall as Alliance, or Dominator's Seal and Dominator's Circle as Horde. Each of these will cost you 1250 VP. At Revered, You'll be able to get a belt, a pair of boots, and another trinket. For Alliance DPS, that's Helmbreaker Medallion, Sea-Soaked Sollerets, and Girdle of Crushing Strength. For Horde DPS, the items are Skullrender Medallion, Cragchewer Sollerets, and Kwon's Crushing Girdle. For Alliance tanks, you can pick up Vaporshield Medallion, Sabatons of the Sullied Shore, and Waistplate of Immobility. Horde tanks will be able to grab Groundbreaker Sabatons, Medallion of Mystifying Vapors, and Immovable Waistplate. All of these will cost 1750 VP each.
Before you start earmarking VP for this gear though, keep a few things in mind. First, at only item level 496, all this VP gear may be a side-grade or even a downgrade from your current gear if you've been raiding and buying VP gear already. Second, we will also be getting the gear upgrade system with patch 5.1. In that case, it may be prudent to spend your VP on upgrade existing gear, especially your weapon if you're DPS. In the end, what will determine what you buy should be based not on what's newest, but what provides the best upgrade for you based on the important stats for your specific spec.
Learn the ropes of endgame play with WoW Insider's DK 101 guide. Make yourself invaluable to your raid group with Mind Freeze and other interrupts, gear up with pre-heroic DPS gear or pre-heroic tank gear, and plot your path to tier 11/valor point DPS gear.