Linux port
The Mac client is no native client. It is actually the original Windows client, running in the (wine-based) emulation software called Cider.
If you manage to run GW2 under wine, for which exists fan-based documentation, you have about the same environment and performance as the Mac client.
Can’t be done without a lot of re-writing of the game engine, so it’s not gonna’ happen.
I like Linux as well, but it would require too much work for a small user base of (exclusive) Linux users.