Healing surges are one of those mechanics in 4E that I am not particularly wild about. Granted, hit points are an abstract representation of injuries taken in combat, so it’s a little absurd to argue that allowing characters to spontaneously heal themselves in the middle of combat for no apparent reason is unrealistic. However, there’s something about the mechanic that just strains my sense of disbelief. On the other hand, I recognize that it sucks when you’re the front line fighter in a combat with a Huge creature that has 15 ft. reach, and the cleric can’t get close enough to heal you without provoking an attack of opportunity. It’s even worse if the cleric is already down, or the party doesn’t even have a healer to begin with. That’s why I’m reluctantly willing to accept that maybe second wind is a necessary mechanic.
Now with that said, I don’t think it’s necessary to make second wind work the way that it does. In my opinion, second wind should work more like a surge of adrenaline. It gives you that temporary burst you need to temporarily ignore serious injuries. However, it comes at a price. That’s why, when I converted these rules to 3.5, I made the hit points granted by second wind temporary, and made it so that characters become fatigued when the hit points wear off. I think this is a nice way to allow players to overcome some of the shortcomings of not having a healer in the party, while still respecting the basic mechanics of Third Edition.
By the way, here’s another interpretation of the second wind action.