I've loved to play stealth games. They are among my top favorites.
I've seen a lot of complaints that "too much" firepower loses the incentive to actually sneak. So whats the point? the point of a stealth game is to sneak right?
The point, to me at least, is less about having incentive to sneak, but respecting the art that is stealth. The sweet subtly of a well placed movement, or a clever plan fall into place is what makes the game, the art, incredible. The point is to up hold the integrity of stealth and subtly.
I have retried countless mission to make it perfect, even if it was just because an enemy was possibly aware of my presence. It is about being nothing and everything in your environment. You are nothing to those around you, but you are everything to the mission, to the objective. Leave everything the way it was, and never make yourself a threat. On the subject of killing: kill when you must? Kill if its your objective, but otherwise there is never a must. A subtle death just a kill, which makes you a killer, not a shadow.
Stealth, in my opinion, is an art that is learned and felt.