Conversely having open ended gameplay also does not make a game better.
From my own experience with most of the open ended games is that the end result has been bland and lackluster where your actions ingame may as well not have occurred for all the utter lack of difference they make in the post main quest gameworld. As no matter what you do during the main quest in most open ended games, the end result is almost always exactly the same which tends to leave me with a feeling of why the blue blazes did I bother doing all that, just so nothing changes. Personally I prefer games which at least leave you/give you an impression that your actions matter and do make a difference in the games world.
Also with regards to the past Fallout games, so far ALL OF THEM have ended in their vanilla state. (Yes, you could continue on in Fallout 2 but that was an option and not an integral part of the standard game, which ended once you finished the main quest and Fallout 3 did get a DLC which allowed you to continue after the end of the game, but it obliterated the games already shaky gameplay balance and made it far to easy to become a J.O.N.T.M.O.A. wasteland godling and far too had to end up with characters who actually had different skillsets). So trying to cite the past Fallout games as why open ended is better than a definitive ending is not really the way to go as they have all had definitive endings.
