"Simply fighting each other with no other objectives or choices to make gets old relatively quickly."
Damnit jay, no. These kind of games the community makes their own fun and their own rules.
Every month you delay release is another month where expectations grow exponentially.
That's what people did in D2, and that's why they're adding dueling to D3 probably next month. Structured PvP most likely wouldn't have had any real customization options.
The main issue with dueling right now is the lack of a public game list. They really need to add that, the matchmaking system is clearly not sufficient.