LoS is essential to arena play, most posters in this thread advocating for arena removal have zero exepirience of facing proper wizard cleaves melting your face without anything to hide behind. Seriously if you can't take a preassure of 2v2 (that can be pretty frustraiting) then play 3v3 (that you're supposed to play to achieve shinies). If you don't know when to pillar and when to push in then try to learn or give it up alltogether.
P.S. DK complaining about Disc... Seriously you can rotate cds and nulify 4 fears of 5, you can stick to him and when you can't - just grip dps and wail on him to force priest heal, switch back and forth to oom priest. If you know how to play DK you'll score a kill on priest eventually or may be will be killed by his hunter or feral, but that's what PvP is about - not just walking over dead bodies.