dtgreene: How about making health regen the effect of a powerup, rather than something automatic?
Alternatively, how about having health regen on the easiest difficulty, but not on other difficulties? (Of coures, this requires there to be a difficulty selection.)
fronzelneekburm: Well, let's put it this way: Health regen simply doesn't work in a Duke Nukem game. A proper Duke Nukem game would ideally revolve around nonstop action. Health regen, on the other hand, is a hold over from cover-based shooters, which are the exact opposite: Get shot, hide behind cover, wait for your health to replenish, wait for the enemy NPC to poke its head out, shoot the enemy, move to your next cover, get shot, rinse and repeat. I find this kind of gameplay excruciatingly boring. The game literally stands in the way of its own action setpieces.
Since we're kinda talking about Duke Nukem's character in this thread, I also think that health regen completely runs counter to his over-the-top action hero persona. The Duke Nukem of yore would enter a room guns blazing, drop a one-liner once the room is cleared and continue on to the next room. He doesn't strike me as the kind to hide behind cover whenever he encounters an enemy.
The devs can leave medkits all over the place, they can make it so easy you're playing it in de facto godmode, but cover mechanics (which health regen definitely is) are the absolute antithesis to what I'd like to see in a Duke Nukem game. Hiding behind cover isn't fun. Blowing shit up is.
Here's an interesting thought:
Collecting a heath regen pick-up before a battle, particularly if the effect has a decent magnitude, may make it unnecessary for a decent player to have to stop to look for instant health items during the middle of combat, allowing the player to focus on actually killing the enemies while not taking too much damage (which would overwhelm the health regen). It also doesn't overly encourage hiding, because while that might be useful to heal a bit, if you do it too much, the pick-up will wear off. (You can also have other power-ups, like increased damage/defense/speed, that wear off if you wait too long.)
Edit: One thing to note: Intant health pick-ups can only heal damage taken before they're picked up, while health regen pick-ups don't have this drawback, and can heal damage taken after they're picked up (at least until they wear off).