Uh, weather?

[BunjiKugashira.9754]

I believe a dev once commented on the topic on the old forums. Basically it boils down to "too much work for too little gain".It isn't enough to slap some clouds in the sky to create cloudy weather. You have to change lighting, shadows, etc in order to make the weather believable. ANet would have to rework every map for every weather-type they want to introduce.

Back then most of the lighting effects were hand crafted and unless ANet wrote some code that can place the lighting automatically it is likely they're still hand crafting most of it.