Must have GCD avaliable to move waypoint marker.

[Velox]

The waypoint is not an actual ability so I fail to see why it was implemented this way.

Actually, this is probably the exact reason why it was. Remember the actual code that handles AoE skills already exists in the game engine. This allows the devs to just create the waypoint marker from this class without having to create it as its own object. What this means is that the marker is a ground-targeted AoE skill that does not do damage nor buff/debuff anything. This way the devs wouldn't have to reinvent the wheel since all the code is already there and can easily be tweaked in a fraction of the time it would take to design it from scratch.

[Viridiana]

Actually, this is probably the exact reason why it was. Remember the actual code that handles AoE skills already exists in the game engine.

As is the code for AoE skills not on GCD. Like Flaming Arrow. >_>

[Velox]

As is the code for AoE skills not on GCD. Like Flaming Arrow. >_>

True, then again they probably weren't even thinking about this when the designed it. Let's face it, having the markers tied to the GCD isn't hugely game-breaking. More or less, what was done was done simply because it was the quickest and easiest way out, even if it wasn't necessarily the right way. Time is money after all.