Maybe we don't have clouds at the moment due to frame rate hits. With all the new details that are currently being rendered, which are causing some not to be able to play the game ... add clouds into the mix and maybe that number will grow even more.
Maybe there is a problem with how clouds are currently being rendered and may be fixed with the new release that is coming. A new terrain editor has been developed and will be released soon. Clouds are a terrain object so maybe the clouds that HT wants to introduce are only available on maps that are made with the new terrain editor.
You have to think why clouds are not being used at the moment. The amount of separate threads on clouds as of late are getting comical. Do you think that HTC is not using clouds just to piss you off ?
We had all sorts of clouds in AH I and now we don't ... think about it. There is a very good reason ... it's just that HT has chosen, at this point, not to tell us why.
As far as night is concerned ... when night can be rendered correctly and a true night environment is simulated, then I could care less if we ever see night again.