First of all: This blog post WILL go into specifics about the ending of Dear Esther. If you have not played it: turn back, play it and get back here.
There has been alot of talk about the ending of Dear Esther and I as a perhaps more than moderately cultured individual, I thought that adding my two cents would be a good idea.
The most interesting point about the ending is not the typical "but what did it mean?" question, for me it´s the loss of control at the last moment.
Allthough the game is almost comepletely linear, you still have a choice of pace and course throughout. You can go where you will, when you will. You are however strongly encouraged to follow to path.
But at the last second this ability is taken away from you, and the character acts on his own in final fatal momentes of the game. Many do not like this, but I think this design choice is entierly justified.
Dear Esther is a game about accepting loss and letting go. The protaganist must come to terms with his own and others´ lack of control, in order to get off the island, and this enforced by taking control away from the player at the last moment.
I you were controlling the protagonist up to the very last moment would not necessarily ruin this point. But it would be harder to get to since most players would end wound up in decifering the meaning of specific story points instead of the overarching theme.
This is of course my own analysis, but I think it is a valid one.