Gotta agree, rather see a long game with lots to do, than a short game that is over before it feels like its begun.
An open world game should never feel like a level based game... the story should never be short... as it;s really a different process altogether. With a level based game, you have to program for each level the objectives and path becuase each level the world resets to a new thing, bound and gagged and restricted to what you can access at that time.
In an open world game the whole world is laid out, and the possibilities for missions and activities within that frame work is near limitless.
Granted some people have ADD, and if they can't finish the game quickly they get bored. But for me, the longer you can put out quality expereinces in an environement, the better the game is.
Give me fallout, sleeping dogs, or GTA over hitman or deus ex or the last of us, any and every day of the week. Give me the ability to enjoy the world at my own pace when not on a mission, to truly get the most out of the developers hard work, and to have my character live the life I choose for them, than a short totally scripted bullshit life. No matter how compelling the story may be in a level base game, it's not my story, it never will be. The choices are always artificial, because I have no agency in the game world to truly do whatever I wish. And RDR, GTA, and Sleeping Dogs more than prove you can tell every bit as compelling a story in an open world setting as with a scripted level based one... it just means you don't have to rely on cut scenes to tell your story for you as much, which is also a bonus as far as I am concerned.