Looking at it from a casuals point of view (I'm not casual just so you know) I can definately see the appeal of cross server dungeons and I'm sure SE are considering it based on that.
They want to make this game a casual MMO, so adding casual features makes sense.
I think it would be best adding this to the 3rd players poll to see what the majority of people think and not just the "noisy" few who post here.
