Invisible wall of GMing?

Browsing various forums again, I came across a topic. The topic eventually discussed fudging the dice (ie: not using the result of the roll). Specifically, it was about character death, but I don't think that the account itself was important, just the subject. Fudging the dice ... versus tweaking the system.

Players (GM included, perhaps at the forefront) fudge the dice for different reasons and in different situations. A common fudge will involve character death. Most people don't want their character to die in a random battle with some kobolds that hold little importance over the story. Therefore, when the situation comes up, the GM will fudge the results. However, the process makes little sense to me.

If everyone wants to be able to die at any time or never wants to die, you have no problem. When people disagree about when characters should die, you have a problem. The problem, however, is likely with the player. Their goals just don't match up with rest of the groups (or sometimes the group itself will be split 3/3 or something). In situations like this, it might be best to find players who agree with you on the matter. Fudging is only going to make people mad when they find out.

When you have a group that all agrees that nobody should die to a random goblin, but that's not how the system works, you have another problem. This, however, isn't something that should just be ignored until you come across is and then fudged. All you have to do is tweak the system. Write down a rule "After initiative, the GM tells the players if they can die in the battle" Make it clear that, even if they won't die to some orcs that they will still be penalized for losing or generally doing dumb things (because they know they can't die). Big deal, so they didn't die. Now they are imprisoned by the gnolls, waiting their turn to be transformed into undead laborers... or Congrats! You took a daring risk in the middle of battle to save a fellow character... only without the risk. Thanks for the effort, but it isn't really heroic.

Don't be afraid to alter the system. You've seen it a million times on TV. Lying eventually leads to a bad situation. I fail to see any reason where fudging would be good, and tweaking would be bad.