The response to pointing this out has been: "Well, obviously we don't hit hard enough if they can kill us three times!!!!", to which the appropriate response is: "If they were able to do 75 to 150K worth of damage to you before you could kill them in return then, with all due respect, you were either countered or simply outclassed. Thanks for playing. Don't let the kick at your ego hit you on the way out the door :)".
There are arguments to be made against these changes, mostly in regard to PvP constantly screwing around with PvE balance, but suggesting the class engage in some sort of screwball bastard child hybrid system of the Death Knight and Warrior classes isn't really where I suspect the game needs to go to fix it. Functionally, it's about finding that sweet spot in PvP survivability where the class isn't getting solo nuked in 3 seconds nor retains a functionally insane health pool unless facing superior numbers and preferably doing so without trashing the classes ability to tank in PvE. The more straightforward method is to move some of the survivability abilities into the Protection tree, where stat buff talents that are being moved to Mastery in Cataclysm will be looking to be replaced, which could then be balanced by mobility talents shifted to the Ret/Holy tree. Start by moving Divine Protection in there: it's primary use is as a shield wall anyways. Or, perhaps better, make Divine Protection the 25 point Protection talent, Divine Shield the 25 point Retribution talent, and Lay on Hands the 25 point Holy talent; deep enough that it's possible to take two yet also in a position where one has to make a choice to drop other talents of interest to do so.
PS: Keep Righteous Fury available to everyone. It's nice when uber heals combine with a Retribution Paladin to make for quick heroic runs :)
* back in Burning Crusade I was in WSG and managed to down a Hunter one on one by effectively using my cooldowns. As Holy. Uber heals or not, and trust me I wasn't even remotely geared for nor knowledgeable of shockadin at the time, these are the kinds of things that just shouldn't happen at equivalent gear/skill levels even if only once every 20 minutes or so.