I notice reading in pvp zone chat than more and more people like myself are fed up with those zerg trains. I participated in some myself for the first months, and now I think its as entertaining as watching paint dry and as challenging as pushing an elevator button ...
It's even spoiling the fun and the sense of immersion when we are all fighting toes to toes in a contest of skills when "tada", the cavalry appears and just ruins the whole thing.
I even think looking at zergs sometime, lurking in stealth in some corners waiting for only them know what, doing nothing, that they just look ridiculous ...
What about a campaign with grouping limited to 4 or 8 people ? Quite simple to implement and it would be a nice place to organise duels that are becoming more and more apealing to many ...