Do you want a game that's fun in its own right, or one where you just want to skip to the end to see how it turns out?The question is asked about games but the conversation was about books as well.
In books I have a very high tolerance for padding - long monologues / tedious bits of poetry, dripping descriptions of landscapes or settings - I just skip them all to get to the meat of the story. I guess I just accept the padding as a marketing necessity in a world where people expect their fantasy novels to have 1000 pages despite the fact that most stories can be told very well in 200. I am fussy about writing style though. I make a very quick decision (within the first 20 pages or so) as to whether this writer has what it takes to keep me reading.
I love finishing games. I get a tremendous buzz from defeating that last boss and seeing the credits roll. I do expect to enjoy myself along the way though. I make a very quick decision about whether or not I will continue to play a game. Usually after one or two playing sessions. If the game manages to hold on to me for that long there is a good chance I will make it to the end. Just as in books I can skip through a lot of padding (I rarely read long quest descriptions for example) but I do like a bit of entertainment along the way.
Of course MMOs don't have an end and in a way that is a problem for me. I don't think I will ever buy into the "we keep playing to upgrade our gear so that we can keep playing" model. Guild wars held on to me longer than WOW and I think the drive to finish the storyline was one reason. Lotro has held on to me longer than either and I think the epic story line is a one big factor. Its not even that the epic story is all that great. Its a far cry from Tolkien and it certainly isn't a story you would read in book form. Yet it provides the thread which directs the game for me and keeps me playing.