I think teamplay should always be more important than "duels". I mean, after all it's a battle, and numbers should count in battles. I see no reason to cater those veterans/no-lifers who win fights against 5+ people on a regular base, as they definitely don't represent the majority. I don't think any good about a game which is fun for 10%, and the remaining 90% are working to have that fun the upper 10% already enjoy.
That said, I also think that "dumbing down" is the entirely wrong expression. It is not dumbed down, rather the opposite, because now not only skill, but also teamplay matters. First of all you need to influence the preconditions of a fight by good teamplay, so that the advantages and numbers are about even, and then, when two equal groups meet, the skill will decide which group will win. So skill still matters a lot, but it's not the only decisive factor. Don't tell me this is dumbing down the game. A game which determines the winner by pure reflexes is dumb, like Counter Strike or Call of Duty.
Edit: I forgot something, but Teeth wrote it down a few posts below: it's not the long stabbing weapons which brought the change, they always existed (most of them). It's the slower gameplay, the long weapons are only the reaction. But I would recommend to only increase it slightly, for the reasons I told in my first two paragraphs. Don't make this game a stage for no-life skill monsters and their one-man-show.