First of all, let me just say that if you think other players will just purposely ruin your game experience with anyway they can, you are not that important and not everything revolve around you. (For the ones bringing up "blablab everyone will group duel near me and ruin MY experience")
Group vs Group duel will bring many good things and basically has no drawback:
1.People you see dueling around now are mostly dps waiting for queue, they wouldn't get in a group to "ruin your experience" because they wouldn't get in a big group.
2.For ppl testing their build or just messing around with friends, group duel with selected people in proper pvp groups without having to go to pvp area (which takes a long time to meet up, has faction restrictions and may have interference) is perfect. ESO never offered group pvp with the people of your choosing (opponent wise at least), and having that is great for testing build within guild etc. And again to ranters, they want to get away from you more than you from them.
3.RP PVP. People can finally try this. As long as you wish to, several guilds can band up together and form a pvp rp community, they can have wars
/siege scenarios that actually involve players fighting and not just bunch of people typing. Overland can be made use and every city town delve etc can be "territory" and guilds fight between each other etc.
Group vs Group pvp in house & overland 37 votes
Aye we need it a long time ago
Maybe in houses, not in overland, for reasons
No people will just use it to troll me