I think that the developer wanted to show you that no matter how hard you try, you can't always get the best/perfect result. That's something I like very much because it makes the game realistic, believable and mature. It was one of the prominent reasons that made games like The Witcher 1/2, Tactics Ogre, DA:O, Arcanum and … so enjoyable for me.


===Edit===
And I am quite satisfied with the [first] ending that I got in DA:O.
As a human noble, I talked Anora into marrying me. I was to be the king, mostly because neither Anora nor Alistair would make a great ruler. Alistair was a fool and Anora was a dictator.
I refused Morrigan because I did not want to bring a demon into this world.
In the end, when I learnt about the great sacrifice that had to be made, I could not let Alistair sacrifice himself, because although he was a fool, he was my [character's] friend. I killed the Archdemon myself and got the ultimate sacrifice ending, Anora became the queen and Alistair ceased his claim to the throne. I would have done otherwise and supported Alistair instead, only if I was aware of the sacrifice before the lands-meet, but in the end I got the best result (and not the perfect result) based on the information that my character had in the lands-meet and my (his) available options at the lands-meet and after the final battle, and even though it was a very bitter ending, the feeling of realism and real choice-consequence made it a very satisfying ending for me.

I really don't dislike the existing endings. At this point, though, I'll take anything over the Mass Effect 3 endings.