WvW, though you can PvP in it, has been set up as a PVe zone and has all the same rules as a PvE zone.
No game can have an area that creates gold without having a cash sink built into it. It would just mean that everyone would run to farm in WvW and make money there because there would be no downside to it. You think you have queues now.
There are people who farm the most effective way they can and if that becomes the most effective way, you'll end up with people coming to WvW to farm and not to fight which, in my opinion, would hurt the WvW community far more than the repair costs do now.