I mean comparatively, how compelling is Master Chief? A guy who runs behind the nearest rock until his imaginary shield recharges and he charges right back into the fight. But shit, for everything Gordon's got, he still cowers like a three year old in a battles against huge odds and relies mainly on chairs, saw blades, and pistol rounds to even get through a level.
As Gordon Freeman, you're backtracking through entire levels for a lucky batch of health, or a desperately needed power pack. As 'Roach' in Modern Warfare 2, you can find weapons littered across the entire level in some of the most precarious places and even on your enemies. Even then their are 300 nicely packed magazines next to the gun, totally unlike Gordon Freeman, you can't pick up a headcrab and hope to use it against the enemy, next thing you know their ripping off your face after you open your pack to pull your RPG.
Half-Life isn't all these other FPS's, where everything you need magically appears around the corner, or the AI Director drops it in strategic places across the map, nor does it allow you anything but what you can find. And That's good. We like that. Because in the end, we're all about the strategy of survival. The guy never speaks, and that's honestly the best. If Gordon Freeman said anything besides "UGH" or "*Breath,breath,breath*" It'd ruin him.
Could you imagine? Friggin Freeman speaking and saying something like "Tentacled" as a scientist is pulled away or "That's what I thought" as he blows up a strider. No. You make your own quips. Your own observations. And in the end, You try your best, and you CONSTANTLY fail.
It's almost an advertisement to that section of the gamer population that believes that when zombies, aliens, or super powered mutant comes, their fat asses will still swing a sword like Tom Cruise in The Last Samurai. Just because you don't have to reload a sword, doesn't mean you're not going to lose a leg to the thing.
When the chips are down, and Gordon Freeman's out of ammo, out of options, and out of health. He'll hold his Gravity gun or Crowbar up as the sounds of enemies draw closer, the glow of mechanical eyes or even Gorgonauts lasers draw near, and he will use the last bits of ammunition, the last ounces of strength and determination, all that he has left to hold out just one second longer for that door to open, or that hack to finish. And in the end, He's only as good as the man behind the curtain.