Having a battleground or designated, and larger, PVP area doesn't mean the game is an MMO.
Personally, I don't see why everyone's just dumping #!## on this idea so quickly. I mean, everyone wanted more players per game, though obviously not thirty-whatever, and a better PVP system. What do you think's being proposed?
They're dumping on it because people around here have an unnatural fear of anything that relates to WoW. They would rather have a less expansive gameplay experience if it ment it was slightly less like WoW.
But what they fail to realize is this will more similarly resemble a Hero Arena from Warcraft3 as opposed to a battleground from WoW because of:
1.) Characters in the Hacknslash genre are far less complicated than characters in MMOs
2.) The 3rd person view gives a 360 degree view of the battlefield, so players are not confined to their own single direction view when moving/fighting
3.) There will be little to no healing involved besides self sustaining potions/orb finds, so combat will pickup and end quickly.
I personally think the idea would be great, it would give variety and replayability if implemented correctly. I can remember playing "Capture the Gold" with groups of friends where a large sum of money would be placed on two ends of the blood moor (I believe this was the name of the very first zone unless my mind is completely failing me) and we would split into offense and defense for each team and try to bring one sum of money back to your own teams gold pile. It was incredibly fun and an actual "mentally engaging" take on normal PvP.