I would like to suggest to implement our Wotlk LoS mechanics also on TBC.

Currently many BGs in TBC are nothing but a "who can abuse hitting through abstacles the best" competition.
Especially when it comes to deffending towers in AV the inexistence of out of line is a disaster.
Mages stay at the bottom of a tower and spam blizzard on deffenders inside the tower flag room.
Melee classes stay on the other side of the tower wall and hit through the wall on opponents inside the tower flag room.

This has realy nothing to do with pvp. Its a massive "hitting through obstacles abuse feast".
I understand that on retail the LoS mechanics were like this back in TBC but I think custom changes realy make sense here.