Igor-Rowan said:
One thing I always wondered is why cover-based shooters (most of them) have regenerating health, while fast paced ones like Painkiller or Doom have health packets, should't it be the other way around? You get in cover and and has to become tactical about the way you manage your health and the way forward and the fast paced one, you can't shoot if you want your health back, adding moments of tension.
Lineage really.
Halo popularized the concept in shooters. Gears of War was also a Microsoft deal and took on the concept itself, and kind of ran with it, and the barrage of chest-high walls scattered across games largely stems from emulating Gears of War. I'd guess it bled into other AAA shooters because before everyone was trying to make CoD, the big FPS target to match (on consoles) was Halo.
On the other side, Doom, and the other run'n'gunners are inspired by well, Doom. And having health packs scattered around provides incentive to mobility. If you can't heal without moving, then trying to hide out in a choke point and plink at enemies becomes a much more adverse proposition.
On the more mechanical side, the regen health is meant to facilitate a lower (or "realistic") time to kill factor, while still allowing recovery so one tiny screw up doesn't mean you're boned. If 3 bullets from a basic enemy killed you in Doom, it'd become impossible in the game as stands. On the multiplayer side, the lowered time to kill facilitates higher scores and gratification in the gameplay. Not that you can't kill people incredibly fast in Doom or Unreal Tournament (or whatever), but its usually related to either an extended application of skill or having controlled the map well enough to pick up the higher tier weapons.