At keep doors, for example, expect heavy AoE damage from the side defending. You won't be able to hit the door with melee attacks without taking a lot of damage. You can still do damage with hit & runs, but imo you'd be more effective at range.
Many that are out of your reach would be reachable with ranged weapons.
Of course, you can still bring two melee sets and be very useful. You can attack smaller targets and smaller groups where massive AoE damage is less of a problem, or where people standing on high unreachable grounds is less of an occurrence. You can even make a point of doing hit & run and dodging the opponent's attacks so they waste their big attacks on you.
But generally speaking, I would want the ranged damage as well as melee damage for flexibility, which imo would be a great asset in WvW.
I cannot overstate the awesomeness that is "Summon Flesh Wurm." It is quite simply the most amazing escape, backdoor, and ambush skill ever.
Just place it somewhere out of the way and teleport to it for a quick escape. Or place it on a hidden hill top, for a quick bait and switch, where you can rain death down upon your enemies after leading them into the kill zone of your warband.
The only disadvantage is that it does seem to have a limit on its teleport range. The range seems to be about half your sight range though, so it's still plenty far. Combine it with a skill to escape snares and you should never be the one to die from any combat encounter...