Recharging shields is a simple intuitive mechanic that I think worked quite nicely to make Halo a strong accessible console shooter. It does however make it far easier to camp than a game with health pickups. Many would argue it dumbs the game down as backing away from a fight to wait a few seconds inherently holds far less risk than having to search for health pickups. At least with Halo 1, by having the health system separate from shields, it meant that if a player was weak after a fight, they would be at a slight disadvantage for their next engagement unless they found a health pack. This forces more movement around a map. Think about how Guardian plays Slayer at any competent level, everyone just camps at the Sniper tower. When they get weak they can back away safely while their team mates cover them, and in a few seconds they are back without a scratch. Imagine though if Halo 3 had health packs and there were some placed away from the tower, now they would have to move out of their power position from time to time. While the Health system doesn't have to be fully pickup based like Quake, I think having at least a subtle health system like CE, allows map designers yet another tool to create movement and prevent camping. I'd say that's always a good thing.