We implemented dueling to provide interested players a way to battle each other -- no objectives, no scoring, just Nephalem against Nephalem. It was something the community has been asking for, and with additional PvP modes still in development we honestly didn't have a good reason to keep saying no.
Dueling isn't intended to be balanced, though, so don't expect a fair fight. That's not what dueling is about. There will probably be some match-ups in which you're one-shotted (this is a big reason why we have no permanent Hardcore deaths at the moment). There will also probably be some match-ups in which you one-shot other players. Your heroes are designed to kill things quickly and without mercy, and in this case those "things" just happen to be other heroes.
We don't anticipate that everyone will like dueling. That's fine. While some players might really love it and find it a cool challenge, we're okay if most people don't make it an integral part of their gaming experience. The system exists to give you the opportunity to obliterate your opponents in an environment designed explicitly for that purpose, but that's it -- and we feel it achieves that goal pretty well.
Now, we're still open to your feedback and will be keeping a close on eye on it throughout the PTR process. We're not opposed to making changes if they benefit the game; in fact, that's what a PTR is all about. In return, we just ask that you keep in mind what the scope of what dueling is supposed to be, and that you give the system a fair shot before jumping to conclusions or making sweeping requests for buffs/debuffs/etc. Explore new builds, try out different tactics, and then let us know what you think. If we make changes, we want them to be informed, and that tends to work out best if the feedback you give us is also informed (i.e. not just a judgment based on only a few minutes of gameplay). :)