They never changed, it, they expanded it to offer more closure. IE, they added sequences with your romance interest, and more personalised ending sequence that emphasized more on the characters you were closer to rather than everyone getting the same.
The ending in essence was the same, and by the way, it didn't suck. What sucked is the self-entitled mankids that couldn't deal with the things that happen in the ending (keeping it spoiler safe).
As all things, a matter of opinion, but as all art, the ending was an artistic choice that I personally embraced in respect to the artists that created the whole masterpiece. It is neither up to me or anyone else other than the creators to change that. Some may like it more or less, but it is what it is, and I personally liked it enough, as a vast majority of players.
What made it seem like the ending sucked is that the players who liked it weren't up raging in flames in the forums, just accepted it, cried a bit with emotion from a great trilogy ending, and moved on with their lives while a vocal minority just kept whining and whining.
As a good salesman would tell you, you never hear a thing from a satisfied customer once they left the store, but from an angry one, you'll never hear the end of it.