Definitely no. A Fallout MMO would almost certainly be based purely on combat, which all people who played the first Fallouts was just a part of the even now very original gameplay of the series. It would mean that the world the game was played in would be fallout, but the gameplay itself will probably be combat. Speech doesn't work for you anymore, because no other player is going to be impressed if you have a high speech skill, they're human. They'll just shoot you in the face and go "WOOOOT I KILLL U NOOOOOOOOB NOW I GOOO FIND WATERCHIP!!". So Speech would be utterly useless, charisma in the SPECIAL system would then be useless as well. Who is going to use repair and science if everyone else in that gameworld is trying to shoot your eyes out? You can throw away a lot of aspects of the original fallouts. Fine, make an MMO based on the Fallout series, but please don't call it Fallout.
Yes and no. I voted Yes because it would work very well if it was made right. I also voted Yes because the Fallout universe would fit an MMO much better than an Elder Scrolls MMO. I'm not sure if it would be a good idea because it would be so easy to turn the game into a poor spin-off that doesn't deserve the title.
Now that I think about it, a Fallout MMO would be one of the few MMOs that would be able to embrace pre-pubascent nerds rapidly typing obscenities and have it actually FIT with some of the style of the franchise. Some, not a lot, but a hell of a lot more understandable than having it in a medieval fantasy setting.
First off, you said you voted Yes because it would work very well if it was made right. There are a lot of threads on this forum that talk about a possible Fallout MMO, and always there are a few people who say it could work well. They do however never explain how they picture a Fallout MMO being done right. So if you could give me any insight on how you think an MMO could be done right, please enlighten me.
I really have to disagree on the second part of what you wrote. In the Fallout games, profanity and some bad language was used in dialogue on a regular basis. It was fun to read and in my opinion it fit right in with the ingame world, but they never really overdid it. Now, if you have an online gameworld in which all kinds of people use bad language all the time, it would definitely not fit in the gameworld, that would be overdoing it. Try playing Diablo 2 online. Especially when that game just got started online, bad language was all over the place ingame and that stuff really got old fast. F-words all over the place, and I really don't mind people cursing, but people were throwing so much crap at eachother, fighting about whatever, it was just bloody awful.