A) In an ideal WvW match, at least one map will be full.
B) Gold is a resource in WvW.
C) Gold can be obtained in PvE, without using up a slot in WvW.
So you can gain an advantage in WvW by playing PvE. Even worse, you can get an advantage in WvW by buying gems, but the fact that PvE currency is a resource in WvW is the root of the problem.
Armor breaking, siege, and upgrades should not cost gold. I’m not going to post suggestions, because this is not the suggestion board. I’m sure Anet can find better punishments for bad play.