Why is there no nights?

After i've seen the haloween thing in game i really wonder this.Why ArenaNet don't make the daylight change by time? I mean for example they can take GMT for European dists and make sun rise/fall or full-moon by time/date. I'm about to get bored of playing always morning (and pls don't say if you want night go Ring Of Fire . It should change too)...

P.S: My English is not good. I'm sorry if there are many mistakes...

I suspect there is no day/night change because it isn't a persistent world, you're playing a game with a linear storyline. Missions take place during a very specific time of the day. It would be pretty silly to have the Riverside Provence mission done during the day, since it is intended to be a stealth mission done during the cover of night.

Missions can be with no change it'll make sense but i think there should changes in towns and quests

I agree that maybe night and day would be a nice addition to the game, however implementing it is a whole different ball game. Because of the huge amount of instances, it would be a require a great deal of recoding from the dev group to make sure all instances are updated on an hourly basis. To be honest this is not really a feesible thing to do, and not at all an advantage for them financially.

That would be interesting to have in towns only (although going from a night sky in town to bright day in a mission would be odd)...it'd be forever dark whenever I played though as I only play at night...unless game time didn't match real time. Maybe if you had 2-4 day/night cycles for every 1 day in real life.

I think they are considering it from some of the hints from the frog and cryptic notes and such. With Halloween they have night skies in lions arch and notice more "weather" patterns in random pvp 4 x 4.

Or you could do a guild wars game time, much like they did on Zelda: Majora's Mask. Of course, the time was much faster than real life, but you did have your days and nights. (and btw, what a true pain it was trying to do the quests on that game in a matter of only 3 in-game days)