" Simply fighting each other with no other objectives or choices to make gets old relatively quickly. We've brought a lot of people in to try out Team Deathmatch and, while some found it entertaining, most of our testers didn't feel like it was something they'd want to do beyond a few hours. Without more varied objectives, or very lucrative rewards, few saw our current iteration as something they'd want spend a lot of time in. "Isn't that what Diablo 2 PVP was, just simply fighting each other with no other objectives.
I don't really know whats changed at blizzard they do way too much thinking.