Well, I think it would be fucking awesome. I have played both Morrowind and Oblivion and I was always stuck thinking "Damnit, why can't my mate and I go stomp on some bandits face?"
See, I got as many companion mods as I could, but the AI is just retarded. I swear I have now spent more time trying to get the Co-Op to work then I have playing the fucking game.
The only mod I ever found with co-op involved me pissing around with some really unfriendly codes to start a server before connecting with a client and playing. And you know what?
It was buggy as shit.
We could only stay outside because right before the maker stopped giving a shit he said that you can only stay outside right now but here's a guide on how to load the insides so you don't have to live in a cardboard box until I fix up the mod so you don't have to. You know what the guide said? Under Progress....
Wow, I have raged for a while and still haven't talked about the co-op. I think that with the right amount of work it would be perfect. You COULD have 64 player co-op like in ArmA 2 but if there are 64 players then there are 1000000000 monsters. Or split screen co-op, but the more players the harder it gets. Simple. Some people talk about the levelling but co-op stands for COOPERATIVE. As in, work TOGETHER to stomp on a goblins face. So who cares about the levelling? A monster is too hard for you? That's why your level 89 buddy is there.
See, the reason I think co-op would be better is because it would open up so many new things. For example, even in my archer class I still had a sword. Why? Because almost all enemies are melee and will charge you. With co-op, however, the archer could make extra wooden limbs appear on enemies, the warrior will hold the enemies off so that the archer doesn't get his buttocks carved into tiny bits. Same with the mages. Half the reason I don't fast travel is because I will find new things if I don't. Because if you don't know its there, you might not stomp on it. See, now I fast travel just because there's nothing new to do.
Co-op could change that, for example you could use your saved character, join a co-op, be plonked into the world. It could be a completely co-op world. So once you out-play the single-player, take your archer into a game and play co-op! The quests could be designed for co-op, like your group goes and attacks a camp. And the world should be random. For example, every hour or whatever make new camps appear, old ones disappear, cities come under attack ect ect.
Then you won't end up with the same world that you now have clocked in both single-player and co-op AND new and exicting things would happen all the time. You might walk past a town. What's all that screaming? Better go have a look. OH BUGGER, an Oblivion Gate just opened onto of my favourite bar! Screw you deamons, I WANT MY ALE! (place epic music, then charge through the gate, close it, and get a well earned glass of ale stalwart hero of the bar.)
It might sound like an MMO but it would be good because it wouldn't end up as your same MMO grind unless you actually wanted to. And if you did, then you probably aren't human.
Play Co-Op,
Rimmy