FPS games do not have the quest/character depth/structure of rpgs and so ti is really easy to balance them... For example, all weapons behave the same for every character in an FPS, all characters in an FPS have the same skill sets, the characters do not have to make multiple choices among quests with conflicting goals. That is why FPS games are so successful as multiplayer games and why even established MMO's like WoW are fighting a never-ending battle with character balance issues.
Yet it is those very differences which make the reward of co-op in an RPG so much more rewarding than in an FPS. You are really taking a friend along as a compainion into a world/life expereince in an RPG, not just having a second gun in a shoot out. Mysteries shall be unravaled together, secluded realms inspected, great achievements made etc.
As to balance problems mentioned by another poster, I doubt they would present nearly the difficulty being suggested. If spells are that polar opposite in effect, the second player would simply not be able to cast that spell whilst the first players was functioning, just like you cannot cast certain ranged spells underwater. I dare say a number of you make a great deal more of the potential problems of co-op implementation than there actually is to them. Also, I will add that the notion of "making the singleplayer experience better" is a red herring argument. The "perfect singleplayer experience" is an island on the distant horizon. . . an island that floats away from the pursuer at a constant rate. The developers could add co-op whilst still exploring the perfect game experience. A game that is perfect in co-op will be no less perfect for a single player, save that it might at times be a tad lonlier. Also the developers pursuit should be the perfect Game, not just the perfect singleplayer experience ( as if such a thing exists), and the perfect game allows the option of co-op for the legions who desire it, just as it allows you to play as a mage if you don't want to be a barbarian, or as a human if you don't like the notion of playing as an orc. To say the effort of making the game have a local co-op option would waste resources better used towards a better gaming experience is little different from me saying, "I like playing as a mage, and so they should dispense with things like Fighter's guild quests so they can focus on a better gaming experience and Mages GUild quest etc." Or, "I like playing as an elf, so they should not put a load of energy into creating skins and the like for stupid argonians and orcs etc. on this new engine, and should instead invest those resources into the following. . . " In short, when looked at objectively, it is seldom considerate to push for limitations on the options of others based upon the fact that you yourself have no desire to excercise those particular options.
Also, it would be best to be more conservative in claiming what a majority of players want or don't want. Elder Scrolls, like most other popular videogames from Fable series to Halo and beyond, have millions of players, only the most minute fraction of which ever poll and post on these forum sites (namely, hardcoe players with a deep connection/interest in the games who come to praise, deride, or push their desires unto the current game or future installments). If a poll of all people who had ever played or bought an Elder Scrolls game were given and the issue of multiplayer were brought up, the majority would likely want it, as most gamers tend to like the option of playing with friends. "No co-op" is a phrase almost never uttered by any except for hardcoe RPG players ( and even amongst us it is far from a universally agreed upon position), some of whom only say it out of dogmatic ridgitity and would be hard pressed to give any solid reasons if asked.
Also, could we dispense with this false equivalancy comment of "there are other games out there for co-op", no Not like Elder Scrolls there aren't There is no game I know of that is quite like Elder Scrolls yet allows for co-op play. Yes there are other RPGs which do, mostly on older engines. And of course, there are the latter Fable games, which are great in their own right, but different in some ways from Elder Scrolls, and certainly not as extensive. Co-op in Elder Scrolls would, at present, be a unique gaming experience. Unique and wonderful. I will not hold my breath for it. . . but I would love to see it. It would be as near as any game has yet come to The Gaming Promised Land. :celebration: