It depends on the type of game if "going back" in a level
should be used.
In a free Gameworld such as Stalker, its part of making
it an exploration world.
Very liniar Games (like Fear, Halflife) should not
send the player back.
But I dont really like liniar games.
The players choice is limited down to follow the
path the gamedesigner defines stricly, and maybe kill
one monster more or less.